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
diff --git a/src/gpu/GrCaps.cpp b/src/gpu/GrCaps.cpp
index 4fb05c1..c544d6e 100644
--- a/src/gpu/GrCaps.cpp
+++ b/src/gpu/GrCaps.cpp
@@ -92,6 +92,7 @@
     fCompressedTexSubImageSupport = false;
     fOversizedStencilSupport = false;
     fTextureBarrierSupport = false;
+    fSampleLocationsSupport = false;
     fUsesMixedSamples = false;
     fSupportsInstancedDraws = false;
     fFullClearIsFree = false;
@@ -165,6 +166,7 @@
     r.appendf("Compressed Update Support          : %s\n", gNY[fCompressedTexSubImageSupport]);
     r.appendf("Oversized Stencil Support          : %s\n", gNY[fOversizedStencilSupport]);
     r.appendf("Texture Barrier Support            : %s\n", gNY[fTextureBarrierSupport]);
+    r.appendf("Sample Locations Support           : %s\n", gNY[fSampleLocationsSupport]);
     r.appendf("Uses Mixed Samples                 : %s\n", gNY[fUsesMixedSamples]);
     r.appendf("Supports instanced draws           : %s\n", gNY[fSupportsInstancedDraws]);
     r.appendf("Full screen clear is free          : %s\n", gNY[fFullClearIsFree]);