add google-build-namespaces to clang-tidy checks

Android's using this check in their clang-tidy builds.

The check itself is well intentioned but doesn't seem to take into
account the particular reason we do this... being able to use these
types and functions from files compiled with different optimization
settings without causing ODR violations or runtime crashes.

Each of the places that's marked is using an anonymous namespace
from a header for good reason, but I don't mind making clang-tidy
ask us to explicitly exempt any others that may come up in the
future.  It's definitely unusual, and rarely the best idea.

Adding -header-filters='.*' actually checks headers...
until now they've been ignored.

Change-Id: Ie421d2b47076bd384b10c7339cfb7a1c3ea90906
Reviewed-on: https://skia-review.googlesource.com/c/176963
Commit-Queue: Mike Klein <mtklein@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
Auto-Submit: Mike Klein <mtklein@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
13 files changed