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

gyp/gm.gyp

 # GYP file to build the "gm" (golden master) executable.
 {
   'includes': [
     'apptype_console.gypi',
   ],
   'targets': [
     {
       'target_name': 'gm_expectations',
       'type': 'static_library',
       'include_dirs' : [
@@ skipping 65 matching lines @@
         }],
         ['skia_os == "win"', {
           'dependencies': [
             'xps.gyp:xps',
           ],
         }],
         ['skia_gpu == 1', {
           'include_dirs': [
             '../src/gpu',
           ],
+          'dependencies': [
+            'gputest.gyp:skgputest',
+          ],
         }],
       ],
     },
   ],
 }
 
 # Local Variables:
 # tab-width:2
 # indent-tabs-mode:nil
 # End:
 # vim: set expandtab tabstop=2 shiftwidth=2: