Init GrGLSLCaps fields from inside GrGLCaps

Fixes circular dependencies by allowing the initialization to be done
intertwined.

BUG=skia:

Review URL: https://codereview.chromium.org/1177053002
diff --git a/include/gpu/GrCaps.h b/include/gpu/GrCaps.h
index f219cb2..727e9fc 100644
--- a/include/gpu/GrCaps.h
+++ b/include/gpu/GrCaps.h
@@ -84,9 +84,8 @@
     bool floatPrecisionVaries() const { return fShaderPrecisionVaries; }
 
 protected:
-    /** Subclasses must call this at the end of their constructors in order to apply caps
-        overrides requested by the client. Note that overrides will only reduce the caps never
-        expand them. */
+    /** Subclasses must call this after initialization in order to apply caps overrides requested by
+        the client. Note that overrides will only reduce the caps never expand them. */
     void applyOptionsOverrides(const GrContextOptions& options);
 
     bool fShaderDerivativeSupport : 1;