Adds support for hardware watchpoints on Arm targets.
This updated patches correct problems in arm hardware watchpoint support patch posted earlier.
This patch has been tested on samsung chromebook (ARM - Linux) and PandaBoard using basic watchpoint test application.
Also it was tested on Nexus 7 Android device.
On chromebook linux we are able to set and clear all types of watchpoints but on android we end up getting a watchpoint packet error because we are not able to call hardware watchpoint ptrace functions successfully.