Add query for block dimensions of a given format

src/opts/SkTextureCompression_opts_none.cpp

 /*
  * Copyright 2014
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkTextureCompression_opts.h"
 
 SkTextureCompressor::CompressionProc
 SkTextureCompressorGetPlatformProc(SkColorType colorType, SkTextureCompressor::Format fmt) {
     return NULL;
 }
+
+bool SkTextureCompressorGetPlatformDims(SkTextureCompressor::Format fmt, int* dimX, int* dimY) {
+    return false;
+}