Improve GLSL integer support

 - Adds shader types for uint.
 - Adds a cap for integer support.
 - Uses glVertexAttribIPointer for integer attribs.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1669853002

Committed: https://skia.googlesource.com/skia/+/3a2caf8ecf38124f4ad21a0f6c4dabfcfa17911a

Review URL: https://codereview.chromium.org/1669853002
diff --git a/src/gpu/GrCaps.cpp b/src/gpu/GrCaps.cpp
index 46f4935..2568e56 100644
--- a/src/gpu/GrCaps.cpp
+++ b/src/gpu/GrCaps.cpp
@@ -15,6 +15,7 @@
     fPathRenderingSupport = false;
     fDstReadInShaderSupport = false;
     fDualSourceBlendingSupport = false;
+    fIntegerSupport = false;
     fShaderPrecisionVaries = false;
 }
 
@@ -50,6 +51,7 @@
     r.appendf("Path Rendering Support             : %s\n", gNY[fPathRenderingSupport]);
     r.appendf("Dst Read In Shader Support         : %s\n", gNY[fDstReadInShaderSupport]);
     r.appendf("Dual Source Blending Support       : %s\n", gNY[fDualSourceBlendingSupport]);
+    r.appendf("Integer Support                    : %s\n", gNY[fIntegerSupport]);
 
     r.appendf("Shader Float Precisions (varies: %s):\n", gNY[fShaderPrecisionVaries]);