improve test setup for test_gl_renderers

tests/runner.py

@@ -11532,8 +11532,7 @@ elif 'browser' in str(sys.argv):
       self.btest('gl_ps_strides.c', reference='gl_ps_strides.png', args=['--preload-file', 'screenshot.png'])
 
     def test_gl_renderers(self):
-      shutil.copyfile(path_from_root('tests', 'screenshot.png'), os.path.join(self.get_dir(), 'screenshot.png'))
-      self.btest('gl_renderers.c', reference='gl_renderers.png', args=['--preload-file', 'screenshot.png'])
+      self.btest('gl_renderers.c', reference='gl_renderers.png', args=['-s', 'GL_UNSAFE_OPTS=0'])
 
     def test_matrix_identity(self):
       self.btest('gl_matrix_identity.c', expected=['-1882984448', '460451840'])