gcc-wrapper: Wrap ld.gold

This ensures that gcc's ‘-fuse-ld=gold’ flag works.

pkgs/build-support/gcc-wrapper/default.nix

@@ -143,6 +143,14 @@ stdenv.mkDerivation {
 
       wrap ld ${./ld-wrapper.sh} $ld
 
+      if [ -e $binutils/bin/ld.gold ]; then
+        wrap ld.gold ${./ld-wrapper.sh} $binutils/bin/ld.gold
+      fi
+
+      if [ -e $binutils/bin/ld.bfd ]; then
+        wrap ld.bfd ${./ld-wrapper.sh} $binutils/bin/ld.bfd
+      fi
+
       if [ -e $gccPath/gcc ]; then
         wrap gcc ${./gcc-wrapper.sh} $gccPath/gcc
         ln -s gcc $out/bin/cc

pkgs/stdenv/adapters.nix

@@ -285,19 +285,13 @@ rec {
     };
 
 
-  /* Modify a stdenv so that it uses the Gold linker. FIXME: should
-     use -fuse-ld=gold instead, but then the ld-wrapper won't be
-     invoked. */
-  useGoldLinker = stdenv:
-    let
-      binutils = stdenv.gcc.binutils;
-      binutils' = pkgs.runCommand "${binutils.name}-gold" { }
-        ''
-          mkdir -p $out/bin
-          ln -s ${binutils}/bin/* $out/bin/
-          ln -sfn ${binutils}/bin/ld.gold $out/bin/ld
-        ''; # */
-    in overrideGCC stdenv (stdenv.gcc.override { binutils = binutils'; });
+  /* Modify a stdenv so that it uses the Gold linker. */
+  useGoldLinker = stdenv: stdenv //
+    { mkDerivation = args: stdenv.mkDerivation (args // {
+        dontStrip = true;
+        NIX_CFLAGS_LINK = toString (args.NIX_CFLAGS_COMPILE or "") + " -fuse-ld=gold";
+      });
+    };
 
   dropCxx = drv: drv.override {
     stdenv = if pkgs.stdenv.isDarwin