Update NaCl ARM build flags now that gcc used as default compiler.

ppapi/native_client/src/untrusted/pnacl_irt_shim/pnacl_irt_shim.gyp

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'includes': [
     '../../../../../native_client/build/untrusted.gypi',
   ],
   'targets': [
     {
       'target_name': 'pnacl_irt_shim',
       'type': 'none',
       'variables': {
         'nlib_target': 'libpnacl_irt_shim.a',
         'out_newlib_arm': '<(SHARED_INTERMEDIATE_DIR)/tc_pnacl_translate/lib-arm/libpnacl_irt_shim.a',
         'out_newlib32': '<(SHARED_INTERMEDIATE_DIR)/tc_pnacl_translate/lib-x86-32/libpnacl_irt_shim.a',
         'out_newlib64': '<(SHARED_INTERMEDIATE_DIR)/tc_pnacl_translate/lib-x86-64/libpnacl_irt_shim.a',
         'build_glibc': 0,
         'build_newlib': 1,
+        'force_arm_pnacl': 1,
         'sources': [
           'pnacl_shim.c',
           'shim_entry.c',
           'shim_ppapi.c',
         ],
         'include_dirs': [
           '../../../..',
         ],
         'extra_args': [
           '--strip-debug',
         ],
         'conditions': [
           ['target_arch=="arm"', {
             'compile_flags': [
               '--pnacl-allow-translate',
               '--pnacl-allow-native',
               '-arch', 'arm',
             ],
           }],
         ],
       },
       'dependencies': [
         '<(DEPTH)/native_client/tools.gyp:prep_toolchain',
       ],
     },
   ],
 }