update our build system to support the experimental L-Release NDK

gyp/gpu.gyp

 # GYP for building gpu
 {
   'target_defaults': {
     'conditions': [
       ['skia_os != "win"', {
         'sources/': [ ['exclude', '_win.(h|cpp)$'],
         ],
       }],
       ['skia_os != "mac"', {
         'sources/': [ ['exclude', '_mac.(h|cpp|m|mm)$'],
@@ skipping 197 matching lines @@
         }, { # not skia_angle
           'sources!': [
             '<@(skgpu_angle_gl_sources)',
           ],
         }],
         [ 'skia_os == "android"', {
           'sources!': [
             '../src/gpu/gl/GrGLDefaultInterface_none.cpp',
             '../src/gpu/gl/GrGLCreateNativeInterface_none.cpp',
           ],
+          'defines': [
+            'GR_GL_USE_NEW_SHADER_SOURCE_SIGNATURE=1',
+          ],
           'link_settings': {
             'libraries': [
               '-lGLESv2',
               '-lEGL',
             ],
           },
         }],
       ],
     },
   ],
 }