Merge remote-tracking branch 'origin/darwin-clang-stdenv' into staging

Conflicts:
	pkgs/applications/editors/vim/macvim.nix

pkgs/servers/http/nginx/default.nix

@@ -112,7 +112,7 @@ stdenv.mkDerivation rec {
     ++ optional (elem stdenv.system (with platforms; linux ++ freebsd)) "--with-file-aio";
 
 
-  additionalFlags = optionalString stdenv.isDarwin "-Wno-error=deprecated-declarations";
+  additionalFlags = optionalString stdenv.isDarwin "-Wno-error=deprecated-declarations -Wno-error=conditional-uninitialized";
 
   preConfigure = ''
     export NIX_CFLAGS_COMPILE="$NIX_CFLAGS_COMPILE -I${libxml2}/include/libxml2 $additionalFlags"

pkgs/servers/x11/xorg/overrides.nix

@@ -69,12 +69,15 @@ in
   };
 
   libX11 = attrs: attrs // {
-    preConfigure = setMalloc0ReturnsNullCrossCompiling;
+    preConfigure = setMalloc0ReturnsNullCrossCompiling + ''
+      sed 's,^as_dummy.*,as_dummy="\$PATH",' -i configure
+    '';
     postInstall =
       ''
         # Remove useless DocBook XML files.
         rm -rf $out/share/doc
       '';
+    CPP = stdenv.lib.optionalString stdenv.isDarwin "clang -E -";
   };
 
   libXfont = attrs: attrs // {
@@ -99,8 +102,11 @@ in
   # Note: most of these are in Requires.private, so maybe builder.sh
   # should propagate them automatically.
   libXt = attrs: attrs // {
-    preConfigure = setMalloc0ReturnsNullCrossCompiling;
+    preConfigure = setMalloc0ReturnsNullCrossCompiling + ''
+      sed 's,^as_dummy.*,as_dummy="\$PATH",' -i configure
+    '';
     propagatedBuildInputs = [ xorg.libSM ];
+    CPP = stdenv.lib.optionalString stdenv.isDarwin "clang -E -";
   };
 
   # See https://bugs.freedesktop.org/show_bug.cgi?id=47792