flip on a bunch of GCC warnings

I've landed fixes for most of these,
leaving -Wclass-memaccess as a TODO.

Bug: skia:9674
Change-Id: Ifb951bc66e022b48ff4b66e4555d3fe3c7ef5aaf
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/257501
Reviewed-by: Ben Wagner aka dogben <benjaminwagner@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
1 file changed