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/development/tools/cdecl/default.nix

@@ -11,7 +11,7 @@ stdenv.mkDerivation {
   preBuild = ''
     ${gnused}/bin/sed 's/getline/cdecl_getline/g' -i cdecl.c;
     makeFlagsArray=(CFLAGS="-DBSD -DUSE_READLINE -std=gnu89" LIBS=-lreadline);
-    makeFlags="$makeFlags PREFIX=$out BINDIR=$out/bin MANDIR=$out/man1 CATDIR=$out/cat1";
+    makeFlags="$makeFlags PREFIX=$out BINDIR=$out/bin MANDIR=$out/man1 CATDIR=$out/cat1 CC=$CC";
     mkdir -p $out/bin;
   '';
   buildInputs = [yacc flex readline ncurses];