gnu: qtbase: Use the store paths for other packages and dynamically loaded libs.

Transfer the applicable NixOS patches as of 2018-01-19:

- Not adopted: We don't change the .cmake.in and .prf, but use config
  mechanisms provided by th Qt build system.

- src/corelib/tools/qtimezoneprivate_tz.cpp: Adopted patch: Use $TZDIR to
  search for time-zone data. Thus avoid depending on package "tzdata", which
  often introduces changes with near-immediate effects, so it's important to
  be able to update it fast.

- src/corelib/kernel/qcoreapplication.cpp: Not adopted: NixOS adds plugin
  paths derived from PATH. We do not need this, since we already have
  native-search-path QT_PLUGIN_PATH.

- src/network/kernel/qdnslookup_unix.cpp,
  src/network/kernel/qhostinfo_unix.cpp: Transferred: Use hard-coded path to
  libresolv.

- src/network/ssl/qsslcontext_openssl.cpp: Not adopted: NixOS changes a
  conditional compilation for Qt 5.9 (but leaves it unchanged for Qt 5.10) to
  fix compilation with libressl.  But Qt does not support libressl anway, see
  config.tests/openssl/openssl.cpp in qtbase 5.9.4.

- src/plugins/platforminputcontexts/compose/generator/qtablegenerator.cpp:
  Transferred: Use hard-coded path to libx11.

- src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp:
  Transferred: Use hard-coded path to mess's libGL, no need for a fall-back.

- src/plugins/platforms/xcb/qxcbcursor.cpp: Transferred: Use hard-coded path
  to Xcursor.

- src/plugins/platformthemes/gtk3/main.cpp: Not adopted: NixOS changes
  $XDG_DATA_DIRS and $GIO_EXTRA_MODULES in the code. We already have a
  search-path-specification for this.

- src/testlib/qtestassert.h: Decided not to adopt this for guix.

* gnu/packages/patches/qtbase-use-TZDIR.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/qt.scm (qtbase): Add comment. [source]: Use new patch.
  [arguments]<#:phases>'patch-paths': New phase.

gnu/local.mk

@@ -1047,6 +1047,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/qemu-CVE-2017-15038.patch		\
   %D%/packages/patches/qemu-CVE-2017-15289.patch		\
   %D%/packages/patches/qt4-ldflags.patch			\
+  %D%/packages/patches/qtbase-use-TZDIR.patch			\
   %D%/packages/patches/qtscript-disable-tests.patch		\
   %D%/packages/patches/quagga-reproducible-build.patch          \
   %D%/packages/patches/quassel-fix-tls-check.patch              \

gnu/packages/patches/qtbase-use-TZDIR.patch

@@ -0,0 +1,39 @@
+Use $TZDIR to search for time-zone data. Thus avoid depending on package
+"tzdata", which often introduces changes with near-immediate effects, so it's
+important to be able to update it fast.
+
+Based on a patch fron NixOS.
+===================================================================
+--- qtbase-opensource-src-5.9.4.orig/src/corelib/tools/qtimezoneprivate_tz.cpp
++++ qtbase-opensource-src-5.9.4/src/corelib/tools/qtimezoneprivate_tz.cpp
+@@ -70,7 +70,11 @@
+ // Parse zone.tab table, assume lists all installed zones, if not will need to read directories
+ static QTzTimeZoneHash loadTzTimeZones()
+ {
+-    QString path = QStringLiteral("/usr/share/zoneinfo/zone.tab");
++    // Try TZDIR first, in case we're running on GuixSD.
++    QString path = QFile::decodeName(qgetenv("TZDIR")) + QStringLiteral("/zone.tab");
++    // Fallback to traditional paths in case we are not on GuixSD.
++    if (!QFile::exists(path))
++        path = QStringLiteral("/usr/share/zoneinfo/zone.tab");
+     if (!QFile::exists(path))
+         path = QStringLiteral("/usr/lib/zoneinfo/zone.tab");
+ 
+@@ -645,6 +649,9 @@
+         if (!tzif.open(QIODevice::ReadOnly))
+             return;
+     } else {
++      // Try TZDIR first, in case we're running on GuixSD.
++      tzif.setFileName(QFile::decodeName(qgetenv("TZDIR")) + QStringLiteral("/") + QString::fromLocal8Bit(ianaId));
++      if (!tzif.open(QIODevice::ReadOnly)) {
+         // Open named tz, try modern path first, if fails try legacy path
+         tzif.setFileName(QLatin1String("/usr/share/zoneinfo/") + QString::fromLocal8Bit(ianaId));
+         if (!tzif.open(QIODevice::ReadOnly)) {
+@@ -652,6 +659,7 @@
+             if (!tzif.open(QIODevice::ReadOnly))
+                 return;
+         }
++      }
+     }
+ 
+     QDataStream ds(&tzif);

gnu/packages/qt.scm

@@ -36,6 +36,7 @@
   #:use-module (guix packages)
   #:use-module (guix utils)
   #:use-module (gnu packages)
+  #:use-module (gnu packages base)
   #:use-module (gnu packages bison)
   #:use-module (gnu packages compression)
   #:use-module (gnu packages cups)
@@ -380,6 +381,8 @@ developers using C++ or QML, a CSS & JavaScript like language.")
              (sha256
               (base32
                "1kq422vb2zaic099pgzwk7c0qzgc3xap6qahw5vklrq0mgivvrk9"))
+             ;; Use TZDIR to avoid depending on package "tzdata".
+             (patches (search-patches "qtbase-use-TZDIR.patch"))
              (modules '((guix build utils)))
              (snippet
                ;; corelib uses bundled harfbuzz, md4, md5, sha3
@@ -541,7 +544,38 @@ developers using C++ or QML, a CSS & JavaScript like language.")
                           "qt_config.prf" "winrt/package_manifest.prf"))
                  (("\\$\\$\\[QT_HOST_DATA/get\\]") archdata)
                  (("\\$\\$\\[QT_HOST_DATA/src\\]") archdata))
-               #t))))))
+               #t)))
+         (add-after 'unpack 'patch-paths
+           ;; Use the absolute paths for dynamically loaded libs, otherwise
+           ;; the lib will be searched in LD_LIBRARY_PATH which typically is
+           ;; not set in guix.
+           (lambda* (#:key inputs #:allow-other-keys)
+             ;; libresolve
+             (let ((glibc (assoc-ref inputs ,(if (%current-target-system)
+                                                 "cross-libc" "libc"))))
+               (substitute* '("src/network/kernel/qdnslookup_unix.cpp"
+                              "src/network/kernel/qhostinfo_unix.cpp")
+                 (("^\\s*(lib.setFileName\\(QLatin1String\\(\")(resolv\"\\)\\);)" _ a b)
+                (string-append a glibc "/lib/lib" b))))
+             ;; X11/locale (compose path)
+             (substitute* "src/plugins/platforminputcontexts/compose/generator/qtablegenerator.cpp"
+               ;; Don't search in /usr/…/X11/locale, …
+               (("^\\s*m_possibleLocations.append\\(QStringLiteral\\(\"/usr/.*/X11/locale\"\\)\\);" line)
+                (string-append "// " line))
+               ;; … but use libx11's path
+               (("^\\s*(m_possibleLocations.append\\(QStringLiteral\\()X11_PREFIX \"(/.*/X11/locale\"\\)\\);)" _ a b)
+                (string-append a "\"" (assoc-ref inputs "libx11") b)))
+             ;; libGL
+             (substitute* "src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp"
+               (("^\\s*(QLibrary lib\\(QLatin1String\\(\")(GL\"\\)\\);)" _ a b)
+                (string-append a (assoc-ref inputs "mesa") "/lib/lib" b)))
+             ;; libXcursor
+             (substitute* "src/plugins/platforms/xcb/qxcbcursor.cpp"
+               (("^\\s*(QLibrary xcursorLib\\(QLatin1String\\(\")(Xcursor\"\\), 1\\);)" _ a b)
+                (string-append a (assoc-ref inputs "libxcursor") "/lib/lib" b))
+               (("^\\s*(xcursorLib.setFileName\\(QLatin1String\\(\")(Xcursor\"\\)\\);)" _ a b)
+                (string-append a (assoc-ref inputs "libxcursor") "/lib/lib" b)))
+             #t)))))
     (native-search-paths
      (list (search-path-specification
             (variable "QMAKEPATH")