treewide: Get rid of all uses of crossConfig

The hack of using `crossConfig` to enforce stricter handling of
dependencies is replaced with a dedicated `strictDeps` for that purpose.
(Experience has shown that my punning was a terrible idea that made more
difficult and embarrising to teach teach.)

Now that is is clear, a few packages now use `strictDeps`, to fix
various bugs:

 - bintools-wrapper and cc-wrapper

pkgs/build-support/bintools-wrapper/default.nix

@@ -186,6 +186,7 @@ stdenv.mkDerivation {
       else throw "unknown emulation for platform: " + targetPlatform.config;
     in targetPlatform.platform.bfdEmulation or (fmt + sep + arch);
 
+  strictDeps = true;
   depsTargetTargetPropagated = extraPackages;
 
   setupHook = ./setup-hook.sh;