Add function to build a ghc standalone archive (OSX/iOS only)

pkgs/development/compilers/ghc/head.nix

@@ -85,8 +85,17 @@ in stdenv.mkDerivation (rec {
 } // stdenv.lib.optionalAttrs (cross != null) {
   name = "${cross.config}-ghc-${version}";
 
+  patches = [ ./ios-linker.patch ];
+
   preConfigure = commonPreConfigure + ''
-    sed 's|#BuildFlavour  = quick-cross|BuildFlavour  = perf-cross|' mk/build.mk.sample > mk/build.mk
+    sed 's|#BuildFlavour  = quick-cross|BuildFlavour  = quick-cross|' mk/build.mk.sample > mk/build.mk
+    echo "GhcRtsCcOpts = -glldb -Og" >> mk/build.mk
+  '';
+
+  postUnpack = ''
+    mkdir -p $out/nix-support
+    mv $sourceRoot $out/nix-support/source
+    sourceRoot=$out/nix-support/source
   '';
 
   configureFlags = [
@@ -103,6 +112,8 @@ in stdenv.mkDerivation (rec {
 
   dontSetConfigureCross = true;
 
+  dontStrip = true;
+
   passthru = {
     inherit bootPkgs cross;