distro: Patch libc to avoid accessing /etc/ld.so.cache and friends.

* distro/packages/base.scm (glibc): Apply `glibc-no-ld-so-cache.patch'.
  (glibc-final): Inherit GLIBC's inputs.
* distro/packages/patches/glibc-no-ld-so-cache.patch: New file.
* Makefile.am (dist_patch_DATA): Add it.

Makefile.am

@@ -75,6 +75,7 @@ patchdir = $(pkgdatadir)/patches
 dist_patch_DATA =						\
   distro/packages/patches/binutils-ld-new-dtags.patch		\
   distro/packages/patches/diffutils-gets-undeclared.patch	\
+  distro/packages/patches/glibc-no-ld-so-cache.patch		\
   distro/packages/patches/guile-1.8-cpp-4.5.patch		\
   distro/packages/patches/guile-default-utf8.patch		\
   distro/packages/patches/guile-relocatable.patch		\

distro/packages/base.scm

@@ -511,6 +511,7 @@ used in the GNU system including the GNU/Linux variant.")
 
    (arguments
     `(#:out-of-source? #t
+      #:patches (list (assoc-ref %build-inputs "patch/ld.so.cache"))
       #:configure-flags
       (list "--enable-add-ons"
             "--sysconfdir=/etc"
@@ -550,6 +551,8 @@ used in the GNU system including the GNU/Linux variant.")
                       ;; 4.7.1.
                       ((" -lgcc_s") ""))))
                 %standard-phases)))
+   (inputs `(("patch/ld.so.cache"
+              ,(search-patch "glibc-no-ld-so-cache.patch"))))
    (synopsis "The GNU C Library")
    (description
     "Any Unix-like operating system needs a C library: the library which
@@ -792,7 +795,8 @@ identifier SYSTEM."
      (propagated-inputs `(("linux-headers" ,linux-libre-headers-boot0)))
      (inputs `( ;; A native GCC is needed to build `cross-rpcgen'.
                ("native-gcc" ,@(assoc-ref %boot0-inputs "gcc"))
-               ,@%boot1-inputs)))))
+               ,@%boot1-inputs
+               ,@(package-inputs glibc))))))      ; patches
 
 (define gcc-boot0-wrapped
   ;; Make the cross-tools GCC-BOOT0 and BINUTILS-BOOT0 available under the

distro/packages/patches/glibc-no-ld-so-cache.patch

@@ -0,0 +1,53 @@
+Disable attempts to use the system-wide /etc/ld.so.cache.  This is
+required on LFS distros to avoid loading the distro's libc.so instead
+of ours.
+
+Patch from Nixpkgs.  Idea by Eelco Dolstra, initial patch by Jack
+Cummings, minor fixups by Shea Levy.
+
+diff -Naur glibc-2.13-orig/elf/ldconfig.c glibc-2.13/elf/ldconfig.c
+--- glibc-2.13-orig/elf/ldconfig.c	2011-01-17 23:34:07.000000000 -0500
++++ glibc-2.13/elf/ldconfig.c	2012-04-10 23:28:45.957492340 -0400
+@@ -51,7 +51,7 @@
+ #endif
+ 
+ #ifndef LD_SO_CONF
+-# define LD_SO_CONF SYSCONFDIR "/ld.so.conf"
++# define LD_SO_CONF PREFIX "/etc/ld.so.conf"
+ #endif
+ 
+ /* Get libc version number.  */
+
+--- glibc-2.16.0/elf/Makefile	2012-06-30 21:12:34.000000000 +0200
++++ glibc-2.16.0/elf/Makefile	2012-11-12 23:52:21.000000000 +0100
+@@ -415,12 +415,12 @@ $(objpfx)ldconfig: $(ldconfig-modules:%=
+ 
+ $(objpfx)pldd: $(pldd-modules:%=$(objpfx)%.o)
+ 
+-SYSCONF-FLAGS := -D'SYSCONFDIR="$(sysconfdir)"'
+-CFLAGS-ldconfig.c = $(SYSCONF-FLAGS) -D'LIBDIR="$(libdir)"' \
++PREFIX-FLAGS := -D'PREFIX="$(sysconfdir)"'
++CFLAGS-ldconfig.c = $(PREFIX-FLAGS) -D'LIBDIR="$(libdir)"' \
+ 		    -D'SLIBDIR="$(slibdir)"' -DIS_IN_ldconfig=1
+-CFLAGS-dl-cache.c = $(SYSCONF-FLAGS)
+-CFLAGS-cache.c = $(SYSCONF-FLAGS)
+-CFLAGS-rtld.c = $(SYSCONF-FLAGS)
++CFLAGS-dl-cache.c = $(PREFIX-FLAGS)
++CFLAGS-cache.c = $(PREFIX-FLAGS)
++CFLAGS-rtld.c = $(PREFIX-FLAGS)
+ 
+ CPPFLAGS-.os += $(if $(filter $(@F),$(patsubst %,%.os,$(all-rtld-routines))),\
+ 		     -DNOT_IN_libc=1 -DIS_IN_rtld=1 -DIN_LIB=rtld)
+
+diff -Naur glibc-2.13-orig/sysdeps/generic/dl-cache.h glibc-2.13/sysdeps/generic/dl-cache.h
+--- glibc-2.13-orig/sysdeps/generic/dl-cache.h	2011-01-17 23:34:07.000000000 -0500
++++ glibc-2.13/sysdeps/generic/dl-cache.h	2012-04-10 23:28:20.077488815 -0400
+@@ -29,7 +29,7 @@
+ #endif
+ 
+ #ifndef LD_SO_CACHE
+-# define LD_SO_CACHE SYSCONFDIR "/ld.so.cache"
++# define LD_SO_CACHE PREFIX "/etc/ld.so.cache"
+ #endif
+ 
+ #ifndef add_system_dir