Remove some unused functions/macros.
Move two functions only used by GrBufferAllocPool there.
We only ever used GrSizeAlignUp with pow 2 alignments. Require that,
rename, move to GrTypesPriv.h (along with GrSizeDivRoundUp).
Change-Id: I1a7248952d1905f16f02de2028d65768b186acee
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/262061
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>