Use system bzip2 on iOS.

BUG=none
TEST=none


Review URL: https://chromiumcodereview.appspot.com/10806010

git-svn-id: http://src.chromium.org/svn/trunk/src/build@148118 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

common.gypi

@@ -877,6 +877,7 @@
       }],  # os_posix==1 and OS!="mac" and OS!="ios"
       ['OS=="ios"', {
         'disable_nacl%': 1,
+        'use_system_bzip2%': 1,
         'use_system_libxml%': 1,
       }],
       ['OS=="android"', {