gyp_packager should repsect output_dir

- Check if 'output_dir=' is already defined in GYP_GENERATOR_FLAGS
  before appending the one generated in the script.
- Reusing out/ with different GYP_DEFINES causes everything to rebuild.
- This change allows the user to use different directories for different
  GYP_DEFINES; it can make sanity checking faster for different
  GYP_DEFINES.

Change-Id: Iffa6880381dabdd80a3aa7777a1d20cc3900f3e3

.gitignore

@@ -5,7 +5,7 @@
 .pydevproject
 .repo
 .settings
-/out/
+/out*
 /packager/base/
 /packager/build/
 /packager/buildtools/

gyp_packager.py

@@ -91,6 +91,8 @@ if __name__ == '__main__':
   if ['--depth' in arg for arg in args].count(True) == 0:
     args.append('--depth=packager')
 
+  if (not os.environ.get('GYP_GENERATOR_FLAGS') or
+      ('output_dir=' not in os.environ.get('GYP_GENERATOR_FLAGS'))):
     output_dir = os.path.join(checkout_dir, 'out')
     gyp_generator_flags = 'output_dir="' + output_dir + '"'
     if os.environ.get('GYP_GENERATOR_FLAGS'):