Support Mac android cross compile.

pylib/gyp/generator/ninja.py

Index: pylib/gyp/generator/ninja.py
===================================================================
--- pylib/gyp/generator/ninja.py	(revision 1452)
+++ pylib/gyp/generator/ninja.py	(working copy)
@@ -1198,6 +1198,7 @@
   global generator_additional_path_sections
   cc_target = os.environ.get('CC.target', os.environ.get('CC', 'cc'))
   flavor = gyp.common.GetFlavor(params)
+  default_variables.setdefault('HOST_OS', gyp.common.GetHostFlavor(params))
   if flavor == 'mac':
     default_variables.setdefault('OS', 'mac')
     default_variables.setdefault('SHARED_LIB_SUFFIX', '.dylib')
@@ -1271,6 +1272,7 @@
                             config_name):
   options = params['options']
   flavor = gyp.common.GetFlavor(params)
+  host_flavor = gyp.common.GetHostFlavor(params)
   generator_flags = params.get('generator_flags', {})
 
   # build_dir: relative path from source root to our output files.
@@ -1285,7 +1287,7 @@
       width=120)
 
   # Put build-time support tools in out/{config_name}.
-  gyp.common.CopyTool(flavor, toplevel_build)
+  gyp.common.CopyTool(host_flavor, toplevel_build)
 
   # Grab make settings for CC/CXX.
   if flavor == 'win':
@@ -1302,7 +1304,7 @@
     if key == 'CXX': cxx = os.path.join(build_to_root, value)
 
   flock = 'flock'
-  if flavor == 'mac':
+  if host_flavor == 'mac':
     flock = './gyp-mac-tool flock'
   master_ninja.variable('cc', os.environ.get('CC', cc))
   master_ninja.variable('cxx', os.environ.get('CXX', cxx))
@@ -1326,7 +1328,7 @@
   else:
     master_ninja.variable('ld_target', flock + ' linker.lock $cxx_target')
 
-  if flavor == 'mac':
+  if host_flavor == 'mac':
     master_ninja.variable('mac_tool', os.path.join('.', 'gyp-mac-tool'))
   master_ninja.newline()
 
@@ -1551,14 +1553,17 @@
       command=('$cc -E -P -Wno-trigraphs -x c $defines $in -o $out && '
                'plutil -convert xml1 $out $out'))
     master_ninja.rule(
-      'mac_tool',
-      description='MACTOOL $mactool_cmd $in',
-      command='$env $mac_tool $mactool_cmd $in $out')
-    master_ninja.rule(
       'package_framework',
       description='PACKAGE FRAMEWORK $out, POSTBUILDS',
       command='$mac_tool package-framework $out $version$postbuilds '
               '&& touch $out')
+
+  if host_flavor == 'mac':
+    master_ninja.rule(
+      'mac_tool',
+      description='MACTOOL $mactool_cmd $in',
+      command='$env $mac_tool $mactool_cmd $in $out')
+
   if flavor == 'win':
     master_ninja.rule(
       'stamp',