cc-wrapper: Learn about target prefixes

This is first step towards getting rid of gcc-wrapper-cross

pkgs/stdenv/darwin/default.nix

@@ -73,6 +73,7 @@ in rec {
           nativeTools  = true;
           nativePrefix = bootstrapTools;
           nativeLibc   = false;
+          hostPlatform = localSystem;
           targetPlatform = localSystem;
           libc         = last.pkgs.darwin.Libsystem;
           isClang      = true;
@@ -296,6 +297,7 @@ in rec {
       inherit shell;
       nativeTools = false;
       nativeLibc  = false;
+      hostPlatform = localSystem;
       targetPlatform = localSystem;
       inherit (pkgs) coreutils binutils gnugrep;
       inherit (pkgs.darwin) dyld;

pkgs/stdenv/freebsd/default.nix

@@ -77,6 +77,7 @@ let inherit (localSystem) system; in
         nativeTools  = true;
         nativePrefix = "/usr";
         nativeLibc   = true;
+        hostPlatform = localSystem;
         targetPlatform = localSystem;
         inherit (prevStage) stdenv;
         cc           = {

pkgs/stdenv/linux/default.nix

@@ -76,6 +76,7 @@ let
              else lib.makeOverridable (import ../../build-support/cc-wrapper) {
           nativeTools = false;
           nativeLibc = false;
+          hostPlatform = localSystem;
           targetPlatform = localSystem;
           cc = prevStage.gcc-unwrapped;
           isGNU = true;
@@ -240,6 +241,7 @@ in
         nativeTools = false;
         nativeLibc = false;
         isGNU = true;
+        hostPlatform = localSystem;
         targetPlatform = localSystem;
         cc = prevStage.gcc-unwrapped;
         libc = self.glibc;

pkgs/stdenv/native/default.nix

@@ -125,6 +125,7 @@ in
         "i686-solaris" = "/usr/gnu";
         "x86_64-solaris" = "/opt/local/gcc47";
       }.${system} or "/usr";
+      hostPlatform = localSystem;
       targetPlatform = localSystem;
       inherit stdenv;
     };

pkgs/stdenv/nix/default.nix

@@ -30,6 +30,7 @@ bootStages ++ [
         nativeTools = false;
         nativePrefix = stdenv.lib.optionalString hostPlatform.isSunOS "/usr";
         nativeLibc = true;
+        hostPlatform = localSystem;
         targetPlatform = localSystem;
         inherit stdenv;
         inherit (prevStage) binutils coreutils gnugrep;