Check allignment of sub heap allocation in vulkan

Certain Vulkan devices will return difference alignment requirements for
a given allocation even if using the same heap. Thus we need to check
this alignment as well when deciding which subheap we want to use in our
memory allocation.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2232803003

Review-Url: https://codereview.chromium.org/2232803003
1 file changed