ninja/win: Put common msvs_system_include_dirs into %INCLUDE%

pylib/gyp/msvs_emulation.py

Index: pylib/gyp/msvs_emulation.py
diff --git a/pylib/gyp/msvs_emulation.py b/pylib/gyp/msvs_emulation.py
index 63593a424d8a792fca896b025cd8e674c438c439..713aa8936c2760d17f14925ab8c7d0159d6ef36a 100644
--- a/pylib/gyp/msvs_emulation.py
+++ b/pylib/gyp/msvs_emulation.py
@@ -897,7 +897,8 @@ def _ExtractCLPath(output_of_where):
     if line.startswith('LOC:'):
       return line[len('LOC:'):].strip()
 
-def GenerateEnvironmentFiles(toplevel_build_dir, generator_flags, open_out):
+def GenerateEnvironmentFiles(toplevel_build_dir, generator_flags,
+                             system_includes, open_out):
   """It's not sufficient to have the absolute path to the compiler, linker,
   etc. on Windows, as those tools rely on .dlls being in the PATH. We also
   need to support both x86 and x64 compilers within the same build (to support
@@ -928,6 +929,12 @@ def GenerateEnvironmentFiles(toplevel_build_dir, generator_flags, open_out):
         args, shell=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
     variables, _ = popen.communicate()
     env = _ExtractImportantEnvironment(variables)
+
+    # Inject system includes from gyp files into INCLUDE.
+    if system_includes:
+      system_includes = system_includes | set(env.get('INCLUDE', '').split(';'))

[scottmg, 2014/07/19 18:49:36]

i think order should be preserved (though i'm not sure what that means when
combining). mostly just that someone could prepend to INCLUDE to inject their
own blah.h i guess.

[Nico, 2014/07/19 23:05:35]

Changed everything to use OrderedDict

+      env['INCLUDE'] = ';'.join(system_includes)
+
     env_block = _FormatAsEnvironmentBlock(env)
     f = open_out(os.path.join(toplevel_build_dir, 'environment.' + arch), 'wb')
     f.write(env_block)