Update libc++/libc++abi build flags.

third_party/libc++abi/libc++abi.gyp

 # Copyright 2015 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.
 
 {
   'targets': [
     {
       'target_name': 'libc++abi',
       'type': 'static_library',
       'toolsets': ['host', 'target'],
@@ skipping 15 matching lines @@
         'trunk/src/exception.cpp',
         'trunk/src/private_typeinfo.cpp',
         'trunk/src/stdexcept.cpp',
         'trunk/src/typeinfo.cpp',
       ],
       'include_dirs': [
         'trunk/include',
         '../libc++/trunk/include'
       ],
       'cflags': [
+        '-fPIC',
         '-fstrict-aliasing',
         '-nostdinc++',
+        '-pthread',
         '-std=c++11',
       ],
       'cflags_cc!': [
         '-fno-exceptions',
         '-fno-rtti',
       ],
       'cflags!': [
         '-fvisibility=hidden',
       ],
-      'ldflags': [
-        '-nodefaultlibs',
-      ],
-      'ldflags!': [
-        '-pthread',
-      ],
-      'libraries': [
-        '-lc',
-        '-lgcc_s',
-        '-lpthread',
-        '-lrt',
-      ]
     },
   ]
 }