Include glGetMultisamplefv API

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1720963002

Committed: https://skia.googlesource.com/skia/+/69c1b24bcaa7cffd59753a75a7f3d155696fcac4

Review URL: https://codereview.chromium.org/1720963002
13 files changed