Add a patcher script to apply patches

1. Patcher is a helper to apply patches to certain repos.
2. It runs in hooks of DEPS after fetching deps successfully.
3. patch.cfg is used to config the patch path and target repo path.
4. These python scripts origin from CEF project.
[Android] Add one patch on third_party/openmax_dl

The patch is part of enabling web audio on xwalk on Android x86.
The patch adds the x86 implementation of FFT in openmax_dl.