gcc: Revive the no-sys-dirs patch

For now, we don't NATIVE_SYSTEM_HEADER_DIR because it breaks the
build. However, it points to Glibc in the Nix store (not /usr/include)
so it's kind of okay.

pkgs/build-support/gcc-wrapper/gcc-wrapper.sh

@@ -77,7 +77,6 @@ if test "$NIX_ENFORCE_PURITY" = "1" -a -n "$NIX_STORE"; then
         n=$((n + 1))
     done
     params=("${rest[@]}")
-    NIX_CFLAGS_COMPILE="$NIX_CFLAGS_COMPILE --sysroot=/var/empty"
 fi
 
 

pkgs/build-support/gcc-wrapper/ld-wrapper.sh

@@ -32,9 +32,6 @@ if test "$NIX_ENFORCE_PURITY" = "1" -a -n "$NIX_STORE" \
             # We cannot skip this; barf.
             echo "impure path \`$p' used in link" >&2
             exit 1
-        elif test "${p:0:9}" = "--sysroot"; then
-            # Our ld is not built with sysroot support (Can we fix that?)
-            :
         else
             rest=("${rest[@]}" "$p")
         fi

pkgs/development/compilers/gcc/4.8/default.nix

@@ -64,6 +64,7 @@ let version = "4.8.3";
     patches = []
       ++ optional enableParallelBuilding ./parallel-bconfig.patch
       ++ optional (cross != null) ./libstdc++-target.patch
+      ++ optional noSysDirs ./no-sys-dirs.patch
       # The GNAT Makefiles did not pay attention to CFLAGS_FOR_TARGET for its
       # target libraries and tools.
       ++ optional langAda ./gnat-cflags.patch

pkgs/development/compilers/gcc/4.8/no-sys-dirs.patch

@@ -0,0 +1,28 @@
+diff -ru -x '*~' gcc-4.8.3-orig/gcc/cppdefault.c gcc-4.8.3/gcc/cppdefault.c
+--- gcc-4.8.3-orig/gcc/cppdefault.c	2013-01-10 21:38:27.000000000 +0100
++++ gcc-4.8.3/gcc/cppdefault.c	2014-08-18 16:20:32.893944536 +0200
+@@ -35,6 +35,8 @@
+ # undef CROSS_INCLUDE_DIR
+ #endif
+ 
++#undef LOCAL_INCLUDE_DIR
++
+ const struct default_include cpp_include_defaults[]
+ #ifdef INCLUDE_DEFAULTS
+ = INCLUDE_DEFAULTS;
+diff -ru -x '*~' gcc-4.8.3-orig/gcc/gcc.c gcc-4.8.3/gcc/gcc.c
+--- gcc-4.8.3-orig/gcc/gcc.c	2014-03-23 12:30:57.000000000 +0100
++++ gcc-4.8.3/gcc/gcc.c	2014-08-18 13:19:32.689201690 +0200
+@@ -1162,10 +1162,10 @@
+ /* Default prefixes to attach to command names.  */
+ 
+ #ifndef STANDARD_STARTFILE_PREFIX_1
+-#define STANDARD_STARTFILE_PREFIX_1 "/lib/"
++#define STANDARD_STARTFILE_PREFIX_1 ""
+ #endif
+ #ifndef STANDARD_STARTFILE_PREFIX_2
+-#define STANDARD_STARTFILE_PREFIX_2 "/usr/lib/"
++#define STANDARD_STARTFILE_PREFIX_2 ""
+ #endif
+ 
+ #ifdef CROSS_DIRECTORY_STRUCTURE  /* Don't use these prefixes for a cross compiler.  */