macro hygiene in SkVx.h

These macros are not meant to leak out of the file.

Change-Id: I7e24f65a3053785410c7fac760fd3af46c5c1f1c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/337739
Auto-Submit: Mike Klein <mtklein@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
Reviewed-by: Chris Dalton <csmartdalton@google.com>
1 file changed