Previous check-ins allow to hit the arm hardware watchpoint, with a workaound to handle the issue

that the inferior cannot execute past the watchpoint-triggering instruction.

The solution is disable the watchpoint before resuming the inferior and make it hardware single step;
when the inferior stops again due to single step, re-enable the watchpoint and disable the single step
to make the inferior able to continue again without obstacle.

rdar://problem/9667960

llvm-svn: 153273