aapt: add support for optional uses-permission
aapt: add support for optional uses-permission

Applications can request a permission with android:required="false".
For example:

<uses-permission android:name="android.permission.READ_PHONE_STATE" android:required="false" />

Make aapt understand such permissions.

Bug: 8522021
Change-Id: I7d3af64e7c3eca608316d5bea19c4ea639dd2b7a

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base