Change occurrences of gcc to the more general cc

This is done for the sake of Yosemite, which does not have gcc, and yet
this change is also compatible with Linux.

pkgs/applications/misc/googleearth/default.nix

@@ -16,7 +16,7 @@ stdenv.mkDerivation {
   nativeBuildInputs = [
     glibc
     glib
-    stdenv.gcc.gcc
+    stdenv.cc.gcc
     libSM 
     libICE 
     libXi 
@@ -59,7 +59,7 @@ stdenv.mkDerivation {
       fullPath=$fullPath:$i/lib
     done
           
-    patchelf --interpreter "$(cat $NIX_GCC/nix-support/dynamic-linker)" \
+    patchelf --interpreter "$(cat $NIX_CC/nix-support/dynamic-linker)" \
       --set-rpath $fullPath \
       $out/opt/googleearth/googleearth-bin