keystore: allow '\0's in keys and add guards for cplusplus.
keystore: allow '\0's in keys and add guards for cplusplus.

Change-Id: I0af6ed7c5d51ce4ca39cb837e475942800cf6e2d

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