i#1551 port to ARM: get_segment_base()
i#1551 port to ARM: get_segment_base()

Implements get_segment_base() for ARM via read_thread_register() and prints
it out with the proper ARM name.  Longer-term we may want to
refactor/rename to avoid "segment".

Review-URL: https://codereview.appspot.com/194850043

bl4ckic3/dynamorio,AmesianX/dynamorio,sigma-random/dynamorio,daksunt/dynamorio,code4bones/dynamorio,daksunt/dynamorio,code4bones/dynamorio,AmesianX/dynamorio,sigma-random/dynamorio,daksunt/dynamorio,bl4ckic3/dynamorio,code4bones/dynamorio,code4bones/dynamorio,bl4ckic3/dynamorio,bl4ckic3/dynamorio,daksunt/dynamorio,sigma-random/dynamorio,sigma-random/dynamorio,daksunt/dynamorio,sigma-random/dynamorio,AmesianX/dynamorio,code4bones/dynamorio,bl4ckic3/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio