Fix Mac ObjC PeerConnection API compilation.

talk/build/merge_ios_libs.gyp

 #
 # libjingle
 # Copyright 2015 Google Inc.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are met:
 #
 #  1. Redistributions of source code must retain the above copyright notice,
 #     this list of conditions and the following disclaimer.
 #  2. Redistributions in binary form must reproduce the above copyright notice,
 #     this list of conditions and the following disclaimer in the documentation
 #     and/or other materials provided with the distribution.
 #  3. The name of the author may not be used to endorse or promote products
 #     derived from this software without specific prior written permission.
 #
 # THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 # WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 # MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 # EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 # PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 # OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 # WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 # OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 # ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 {
   'includes': ['common.gypi',],
   'conditions': [
-    ['OS=="ios" or (OS=="mac" and mac_sdk>="10.8")', {
+    ['OS=="ios" or OS=="mac"', {
       'targets': [
         {
           'target_name': 'libjingle_peerconnection_objc_no_op',
           'includes': [ 'objc_app.gypi' ],
           'type': 'executable',
           'dependencies': [
             '<(webrtc_root)/system_wrappers/system_wrappers.gyp:field_trial_default',
             '../libjingle.gyp:libjingle_peerconnection_objc',
           ],
           'sources': ['<(DEPTH)/webrtc/build/no_op.cc',],
         },
       ],
     }]
   ],
 }