Add bench for rectanizers

gyp/bench.gypi

 {
   'include_dirs': [
     '../src/core',
     '../src/effects',
     '../src/utils',
     '../tools',
   ],
   'dependencies': [
     'skia_lib.gyp:skia_lib',
   ],
@@ skipping 52 matching lines @@
     '../bench/PathIterBench.cpp',
     '../bench/PathUtilsBench.cpp',
     '../bench/PerlinNoiseBench.cpp',
     '../bench/PicturePlaybackBench.cpp',
     '../bench/PictureRecordBench.cpp',
     '../bench/PremulAndUnpremulAlphaOpsBench.cpp',
     '../bench/QuadTreeBench.cpp',
     '../bench/RTreeBench.cpp',
     '../bench/ReadPixBench.cpp',
     '../bench/RectBench.cpp',
+    '../bench/RectanizerBench.cpp',
     '../bench/RectoriBench.cpp',
     '../bench/RefCntBench.cpp',
     '../bench/RegionBench.cpp',
     '../bench/RegionContainBench.cpp',
     '../bench/RepeatTileBench.cpp',
     '../bench/ScalarBench.cpp',
     '../bench/ShaderMaskBench.cpp',
     '../bench/SkipZeroesBench.cpp',
     '../bench/SortBench.cpp',
     '../bench/StackBench.cpp',
     '../bench/StrokeBench.cpp',
     '../bench/TableBench.cpp',
     '../bench/TextBench.cpp',
     '../bench/TileBench.cpp',
     '../bench/VertBench.cpp',
     '../bench/WritePixelsBench.cpp',
     '../bench/WriterBench.cpp',
     '../bench/XfermodeBench.cpp',
   ],
 }