Improve NaCl support

- Add nacl_make script to build Skia targets for NaCl using gyp
- Add nacl_interface for command-line apps
- Add nacl_sample as front-end for SampleApp
- Add freetype to DEPS
- Various gyp tweaks for NaCl

TODO:
- Implement GL interface
- Implement font host
- Fix plumbing so that SampleApp works properly
Review URL: https://codereview.appspot.com/6671044

git-svn-id: http://skia.googlecode.com/svn/trunk@6245 2bbb7eff-a529-9590-31e7-b0007b416f81
27 files changed