android: Remove unused --stamp option from dex.py.

build/android/gyp/dex.py

Index: build/android/gyp/dex.py
diff --git a/build/android/gyp/dex.py b/build/android/gyp/dex.py
index 1e6ca8aeee76e2d19057d3f3c3614565e1d9d76e..e90f067206ef2c9a3a3a8a0967c4e7b70ffc5a2a 100755
--- a/build/android/gyp/dex.py
+++ b/build/android/gyp/dex.py
@@ -44,7 +44,6 @@ def main(argv):
                           'is enabled.'))
   parser.add_option('--no-locals',
                     help='Exclude locals list from the dex file.')
-  parser.add_option('--stamp', help='Path to touch on success.')
 
   # TODO(newt): remove this once http://crbug.com/177552 is fixed in ninja.
   parser.add_option('--ignore', help='Ignored.')
@@ -57,9 +56,6 @@ def main(argv):
 
   DoDex(options, paths)
 
-  if options.stamp:
-    build_utils.Touch(options.stamp)
-
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))