gcc: Don't symlink lib and lib64 when building multilib

pkgs/development/compilers/gcc/4.6/builder.sh

@@ -198,7 +198,7 @@ postConfigure() {
 
 preInstall() {
     # Make ‘lib64’ a symlink to ‘lib’.
-    if [ -n "$is64bit" ]; then
+    if [ -n "$is64bit" -a -z "$enableMultilib" ]; then
         mkdir -p $out/lib
         ln -s lib $out/lib64
     fi

pkgs/development/compilers/gcc/4.6/default.nix

@@ -192,7 +192,7 @@ stdenv.mkDerivation ({
     inherit langC langCC langFortran langJava langAda langGo;
   };
 
-  inherit patches;
+  inherit patches enableMultilib;
 
   postPatch =
     if (stdenv.isGNU
@@ -431,7 +431,7 @@ stdenv.mkDerivation ({
     else null;
 
   passthru = { inherit langC langCC langAda langFortran langVhdl
-      langGo enableMultilib version; };
+      langGo version; };
 
   enableParallelBuilding = true;