cc-wrapper: Use stdenvNoCC to build

cc-wrapper may wrap a cc-compiler, but it doesn't need one to build
itself. (c.f. expand-response-params is a separate derivation.) This
helps avoid cycles on the cross stuff, in addition to removing a
useless dependency edge.

I could have been super careful with overrides in the stdenv to avoid
the mass rebuild, but I don't think it's worth it.

pkgs/stdenv/darwin/default.nix

@@ -77,7 +77,7 @@ in rec {
 
         cc = if isNull last then "/dev/null" else import ../../build-support/cc-wrapper {
           inherit shell;
-          inherit (last) stdenv;
+          inherit (last) stdenvNoCC;
 
           nativeTools  = false;
           nativeLibc   = false;
@@ -324,7 +324,7 @@ in rec {
     shell       = "${pkgs.bash}/bin/bash";
 
     cc = lib.callPackageWith {} ../../build-support/cc-wrapper {
-      inherit (pkgs) stdenv;
+      inherit (pkgs) stdenvNoCC;
       inherit shell;
       nativeTools = false;
       nativeLibc  = false;

pkgs/stdenv/freebsd/default.nix

@@ -77,7 +77,7 @@ let inherit (localSystem) system; in
         nativeTools  = true;
         nativePrefix = "/usr";
         nativeLibc   = true;
-        inherit (prevStage) stdenv;
+        stdenvNoCC = prevStage.stdenv;
         cc           = {
           name    = "clang-9.9.9";
           cc      = "/usr";

pkgs/stdenv/linux/default.nix

@@ -84,7 +84,7 @@ let
           libc = prevStage.glibc;
           inherit (prevStage) binutils coreutils gnugrep;
           name = name;
-          stdenv = prevStage.ccWrapperStdenv;
+          stdenvNoCC = prevStage.ccWrapperStdenv;
         };
 
         extraAttrs = {
@@ -244,7 +244,7 @@ in
         };
         cc = prevStage.gcc-unwrapped;
         libc = self.glibc;
-        inherit (self) stdenv binutils coreutils gnugrep;
+        inherit (self) stdenvNoCC binutils coreutils gnugrep;
         name = "";
         shell = self.bash + "/bin/bash";
       };

pkgs/stdenv/native/default.nix

@@ -117,6 +117,7 @@ in
       cc = null;
       fetchurl = null;
     };
+    stdenvNoCC = stdenv;
 
     cc = import ../../build-support/cc-wrapper {
       name = "cc-native";
@@ -126,7 +127,7 @@ in
         "i686-solaris" = "/usr/gnu";
         "x86_64-solaris" = "/opt/local/gcc47";
       }.${system} or "/usr";
-      inherit stdenv;
+      inherit stdenvNoCC;
     };
 
     fetchurl = import ../../build-support/fetchurl {

pkgs/stdenv/nix/default.nix

@@ -1,5 +1,5 @@
 { lib
-, crossSystem, config
+, crossSystem, config, overlays
 , bootStages
 , ...
 }:
@@ -7,9 +7,7 @@
 assert crossSystem == null;
 
 bootStages ++ [
-  (prevStage: let
-    inherit (prevStage) stdenv;
-  in {
+  (prevStage: {
     inherit config overlays;
 
     stdenv = import ../generic rec {
@@ -27,10 +25,9 @@ bootStages ++ [
 
       cc = import ../../build-support/cc-wrapper {
         nativeTools = false;
-        nativePrefix = stdenv.lib.optionalString hostPlatform.isSunOS "/usr";
+        nativePrefix = lib.optionalString hostPlatform.isSunOS "/usr";
         nativeLibc = true;
-        inherit stdenv;
-        inherit (prevStage) binutils coreutils gnugrep;
+        inherit (prevStage) stdenvNoCC binutils coreutils gnugrep;
         cc = prevStage.gcc.cc;
         isGNU = true;
         shell = prevStage.bash + "/bin/sh";
@@ -38,7 +35,7 @@ bootStages ++ [
 
       shell = prevStage.bash + "/bin/sh";
 
-      fetchurlBoot = stdenv.fetchurlBoot;
+      fetchurlBoot = prevStage.stdenv.fetchurlBoot;
 
       overrides = self: super: {
         inherit cc;