Create new target to hold gpu test code, enable direct testing of GrEffects in GM.

gyp/SampleApp.gyp

 {
   'variables': {
     #manually set sample_pdf_file_viewer to 1 to have the PdfViewer in SampleApp
     'sample_pdf_file_viewer%': 0,
   },
   'targets': [
     {
       'target_name': 'SampleApp',
       'type': 'executable',
       'mac_bundle' : 1,
@@ skipping 282 matching lines @@
           ],
           'dependencies!': [
             'animator.gyp:animator',
             'experimental.gyp:experimental',
           ],
           'dependencies': [
             'android_deps.gyp:Android_SampleApp',
           ],
         }],
         [ 'skia_gpu == 1', {
-          'include_dirs': [
-            '../src/gpu', # To pull gl/GrGLUtil.h
+          'dependencies': [
+            'gputest.gyp:skgputest',
           ],
         }],
         [ 'skia_os == "nacl"', {
           'sources': [
             '../../nacl/src/nacl_sample.cpp',
           ],
         }],
       ],
       'msvs_settings': {
         'VCLinkerTool': {
           'SubSystem': '2',
         },
       },
     },
   ],
 }
 
 # Local Variables:
 # tab-width:2
 # indent-tabs-mode:nil
 # End:
 # vim: set expandtab tabstop=2 shiftwidth=2: