Add an accompanying option to the 'frame variable -w' command to, instead of watching the variable,

watch the location pointed to by the variable.  An example,

(lldb) frame variable -w write -x 1 -g g_char_ptr
(char *) g_char_ptr = 0x0000000100100860 ""...
Watchpoint created: WatchpointLocation 1: addr = 0x100100860 size = 1 state = enabled type = w
    declare @ '/Volumes/data/lldb/svn/trunk/test/functionalities/watchpoint/hello_watchlocation/main.cpp:21'

...

(lldb) c
Process 3936 resuming

...

rocess 3936 stopped
* thread #2: tid = 0x3403, 0x00000001000009b7 a.out`do_bad_thing_with_location(char*, char) + 23 at main.cpp:27, stop reason = watchpoint 1
    frame #0: 0x00000001000009b7 a.out`do_bad_thing_with_location(char*, char) + 23 at main.cpp:27
   24  	do_bad_thing_with_location(char *char_ptr, char new_val)
   25  	{
   26  	    *char_ptr = new_val;
-> 27  	}
   28  	
   29  	uint32_t access_pool (uint32_t flag = 0);
   30  	
(lldb) 

Also add TestWatchLocation.py test to exercise this functionality.

llvm-svn: 140836