- Use .cc and .h everywhere.
- Update includes/include guards.
- Remove extra makefile targets necessitated by previous mix
of cpp/cc.
Change-Id: I7aad29152d4177937f8f42927c16c6572228c104
Move file utility classes and functions from testing/test_util to
common/file_util, and make them part of libwebm.
Change-Id: If5b25a63b20efacc16b0fecaa8876ade4ecc4b26