Merge third_party/mesa/src from https://chromium.googlesource.com/chromium/deps/mesa.git at 6da96107e2467063c72e1ec5804f0618a6ce83d3

This commit was generated by merge_from_chromium.py.

Change-Id: I235a6d60e80e6c5546a00c36bf054b4c45dc2c29