gnu: hdf5: Have configure honor SOURCE_DATE_EPOCH.

* gnu/packages/patches/hdf5-config-date.patch: New patch.
* gnu/packages/maths.scm (hdf5)[source]: Use it.
* gnu-system.am (dist_patch_DATA): Add it.

gnu/local.mk

@@ -531,6 +531,7 @@ dist_patch_DATA =						\
   gnu/packages/patches/gtk2-respect-GUIX_GTK2_PATH.patch	\
   gnu/packages/patches/gtk3-respect-GUIX_GTK3_PATH.patch	\
   gnu/packages/patches/gtkglext-disable-disable-deprecated.patch \
+  gnu/packages/patches/hdf5-config-date.patch			\
   gnu/packages/patches/hop-bigloo-4.0b.patch			\
   gnu/packages/patches/hop-linker-flags.patch			\
   gnu/packages/patches/hydra-automake-1.15.patch		\

gnu/packages/maths.scm

@@ -414,7 +414,8 @@ plotting engine by third-party applications like Octave.")
                           version "/src/hdf5-"
                           version ".tar.bz2"))
       (sha256
-       (base32 "0sj8x0gfs5fb28gipnynb9wpkz113h8wq9sva9mxx66kv27xsdgw"))))
+       (base32 "0sj8x0gfs5fb28gipnynb9wpkz113h8wq9sva9mxx66kv27xsdgw"))
+      (patches (list (search-patch "hdf5-config-date.patch")))))
     (build-system gnu-build-system)
     (inputs
      `(("zlib" ,zlib)))
@@ -424,7 +425,8 @@ plotting engine by third-party applications like Octave.")
          (add-before 'configure 'patch-configure
            (lambda _
              (substitute* "configure"
-               (("/bin/mv") "mv"))))
+               (("/bin/mv") "mv"))
+             #t))
          (add-after 'install 'patch-references
            (lambda* (#:key inputs outputs #:allow-other-keys)
              (let ((bin (string-append (assoc-ref outputs "out") "/bin"))

gnu/packages/patches/hdf5-config-date.patch

@@ -0,0 +1,21 @@
+Honor SOURCE_DATE_EPOCH when exporting configuration date.
+Autoconf-level patch submitted upstream on Wed Apr 13 17:03:23 UTC 2016
+
+--- a/configure
++++ b/configure
+@@ -27737,7 +28573,14 @@
+ 
+ 
+ ## Configuration date
+- CONFIG_DATE="`date`"
++ CONFIG_DATE="`date -u`"
++if test -n "$SOURCE_DATE_EPOCH"; then
++  CONFIG_DATE=`date -u -d "@$SOURCE_DATE_EPOCH" 2>/dev/null \
++               || date -u -r "$SOURCE_DATE_EPOCH" 2>/dev/null`
++  if test -z "$CONFIG_DATE"; then
++    as_fn_error $? "malformed SOURCE_DATE_EPOCH" "$LINENO" 5
++  fi
++fi
+ 
+ ## User doing the configuration
+  CONFIG_USER="`whoami`@`hostname`"