Respect SK_FORCE_8_BYTE_ALIGNMENT in GrBlockAllocator

We have unit tests for over-aligned allocation requests (which I know
caught bad addresses on other platforms, but my guess is that wasm's
malloc just so happened to produce pointers at 16 byte boundaries when
they were run). And in the wild, we only would ever allocate things on 8
bytes anyways, so it'd never trigger then. This is mostly to ensure that
if were ever to request something at 16bytes on wasm, the block
allocator's address padding will kick in and do the right thing.

Change-Id: I4b9e3ae5775e453cbbe05bebe4dbe69742a51354
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/303658
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
3 files changed