Cleanup: More override fixes.

Fixes errors like:

../../src/gpu/GrGeometryProcessor.h:172:25: error: 'name' overrides a member function but is not marked 'override' [-Werror,-Winconsistent-missing-override]
    virtual const char* name() const = 0;
                            ^
../../include/gpu/GrProcessor.h:66:25: note: overridden virtual function is here
                                virtual const char* name() const = 0;

BUG=skia:3075
TEST=ninja -C out/Debug skia_lib
TBR=mtklein@google.com

Review URL: https://codereview.chromium.org/789343003
diff --git a/src/gpu/effects/GrCoverageSetOpXP.h b/src/gpu/effects/GrCoverageSetOpXP.h
index 8f85d06..327d3c0 100644
--- a/src/gpu/effects/GrCoverageSetOpXP.h
+++ b/src/gpu/effects/GrCoverageSetOpXP.h
@@ -28,7 +28,7 @@
 
     ~GrCoverageSetOpXP() SK_OVERRIDE;
 
-    virtual const char* name() const { return "Coverage Set Op"; }
+    virtual const char* name() const SK_OVERRIDE { return "Coverage Set Op"; }
 
     void getGLProcessorKey(const GrGLCaps& caps, GrProcessorKeyBuilder* b) const SK_OVERRIDE;