Add depfile support to android build scripts

build/android/gyp/gcc_preprocess.py

Index: build/android/gyp/gcc_preprocess.py
diff --git a/build/android/gyp/gcc_preprocess.py b/build/android/gyp/gcc_preprocess.py
index d816741e62acbb29c5271d435091f8b5dceb6e7e..b0c5da281242ed0b90fd874139fd8ad6182d3f84 100755
--- a/build/android/gyp/gcc_preprocess.py
+++ b/build/android/gyp/gcc_preprocess.py
@@ -31,6 +31,8 @@ def DoGcc(options):
 
 def main():
   parser = optparse.OptionParser()
+  build_utils.AddDepfileOption(parser)
+
   parser.add_option('--include-path', help='Include path for gcc.')
   parser.add_option('--template', help='Path to template.')
   parser.add_option('--output', help='Path for generated file.')
@@ -41,6 +43,11 @@ def main():
 
   DoGcc(options)
 
+  if options.depfile:
+    build_utils.WriteDepfile(
+        options.depfile,
+        build_utils.GetPythonDependencies())
+
   if options.stamp:
     build_utils.Touch(options.stamp)