centralize and clean up disabled warnings

It's easier to handle these all together.
A few don't seem to trigger for me anymore, so they're removed.

It seems easier to just paper over the one -Wbad-function-cast
site than to disable it.

Change-Id: I9edccf99b304240cf26d0b237d0c068f47c6331c
Reviewed-on: https://skia-review.googlesource.com/139166
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: Mike Klein <mtklein@chromium.org>
Reviewed-by: Brian Osman <brianosman@google.com>
7 files changed