Android backend: tidy up the --suffix handling.
Android backend: tidy up the --suffix handling.

Make --suffix .foo generate a makefile called GypAndroid.foo.mk,
instead of GypAndroid.mk.foo.
Review URL: https://codereview.chromium.org/11418007
witwall/gyp,witwall/gyp,witwall/gyp,witwall/gyp,witwall/gyp