add clang variable for other apps to use

libyuv.gyp

 # Copyright 2011 The LibYuv Project Authors. All rights reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS. All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 {
   'includes': [
@@ skipping 16 matching lines @@
          }, {
            'use_sysroot%': 1,
          }],
        ],
     },
     'use_sysroot%': '<(use_sysroot)',
     'use_system_libjpeg%': 0,
     'libyuv_disable_jpeg%': 0,
     # 'chromium_code' treats libyuv as internal and increases warning level.
     'chromium_code': 1,
+    # clang compiler default variable usable by other apps that include libyuv.
+    'clang%': 0,
     # Link-Time Optimizations.
     'use_lto%': 0,
     'build_neon': 0,
     'conditions': [
        ['(target_arch == "armv7" or target_arch == "armv7s" or \
        (target_arch == "arm" and arm_version >= 7) or target_arch == "arm64")\
        and (arm_neon == 1 or arm_neon_optional == 1)',
        {
          'build_neon': 1,
        }],
@@ skipping 104 matching lines @@
       ],
     },
   ], # targets.
 }
 
 # Local Variables:
 # tab-width:2
 # indent-tabs-mode:nil
 # End:
 # vim: set expandtab tabstop=2 shiftwidth=2: