Build PPAPI PNaCl Newlib tests with GN

build/config/nacl/config.gni

Index: build/config/nacl/config.gni
diff --git a/build/config/nacl/config.gni b/build/config/nacl/config.gni
index 887c853a3d25eeda9fa83411ab2853b5f591aef9..9747059bdb4b0c555da85bd7ee08ba72150b49e9 100644
--- a/build/config/nacl/config.gni
+++ b/build/config/nacl/config.gni
@@ -2,6 +2,9 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+nacl_toolchain_dir = rebase_path("//native_client/toolchain", root_build_dir)
+os_toolchain_dir = "${nacl_toolchain_dir}/${host_os}_x86"

[brettw, 2015/10/01 17:27:36]

Since this is going to be basically a global variable now, I think it would be
best to have "nacl" in the name somewhere. I'm not sure enough if what this is
to be able to suggest a good name, though. Can these also have comments, for the
same reason?

I normally put declare_args at the top, and other stuff below it.

[Petr Hosek, 2015/10/03 05:25:27]

Done.

+
 declare_args() {
   # Native Client supports both Newlib and Glibc C libraries where Newlib
   # is assumed to be the default one; use this to determine whether Glibc