Add StackBench to measure performance on stack-like (fixed element size) work loads.

gyp/bench.gyp

 # GYP file to build performance testbench.
 #
 {
   'includes': [
     'apptype_console.gypi',
   ],
   'targets': [
     {
       'target_name': 'bench',
       'type': 'executable',
@@ skipping 65 matching lines @@
         '../bench/RectBench.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',
 
         '../bench/SkBenchLogger.cpp',
@@ skipping 61 matching lines @@
         ['skia_gpu == 1', {
           'sources': [
             '../bench/BenchGpuTimer_gl.h',
             '../bench/BenchGpuTimer_gl.cpp',
           ],
         }],
       ],
     }
   ],
 }