runCommand: Use stdenvNoCC

This ensures that most "trivial" derivations used to build NixOS
configurations no longer depend on GCC. For commands that do invoke
gcc, there is runCommandCC.

pkgs/top-level/default.nix

@@ -82,7 +82,7 @@ let
 
       trivialBuilders = self: super:
         (import ../build-support/trivial-builders.nix {
-          inherit lib; inherit (self) stdenv; inherit (self.xorg) lndir;
+          inherit lib; inherit (self) stdenv stdenvNoCC; inherit (self.xorg) lndir;
         });
 
       stdenvDefault = self: super: (import ./stdenv.nix topLevelArguments) {} pkgs;