Support DEVELOPER_DIR in gyp-ninja for mac.

pylib/gyp/common.py

Index: pylib/gyp/common.py
diff --git a/pylib/gyp/common.py b/pylib/gyp/common.py
index 256e3f3a6b2400f13c1b85c7e6f9668a258a1b95..a1e1db5f1239ff3f3aa2ef4a949f752bbad0415d 100644
--- a/pylib/gyp/common.py
+++ b/pylib/gyp/common.py
@@ -433,7 +433,7 @@ def GetFlavor(params):
   return 'linux'
 
 
-def CopyTool(flavor, out_path):
+def CopyTool(flavor, out_path, generator_flags={}):
   """Finds (flock|mac|win)_tool.gyp in the gyp directory and copies it
   to |out_path|."""
   # aix and solaris just need flock emulation. mac and win use more complicated
@@ -453,11 +453,18 @@ def CopyTool(flavor, out_path):
   with open(source_path) as source_file:
     source = source_file.readlines()
 
+  # Set custom header flags.
+  header = '# Generated by gyp. Do not edit.\n'
+  mac_toolchain_dir =  generator_flags.get('mac_toolchain_dir', None)
+  if flavor == 'mac' and mac_toolchain_dir:
+    header += "import os;\nos.environ['DEVELOPER_DIR']='%s'\n" \
+        % mac_toolchain_dir
+
   # Add header and write it out.
   tool_path = os.path.join(out_path, 'gyp-%s-tool' % prefix)
   with open(tool_path, 'w') as tool_file:
     tool_file.write(
-        ''.join([source[0], '# Generated by gyp. Do not edit.\n'] + source[1:]))
+        ''.join([source[0], header] + source[1:]))
 
   # Make file executable.
   os.chmod(tool_path, 0755)