Require initializers on const variable declarations

Bug: skia:10837
Change-Id: I33da2eb1e723ed04ab62d65c21e54306dd362bed
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/372677
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
4 files changed