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