set a watchpoint Pythonically. If the find-and-watch-a-variable operation
fails, an invalid SBValue is returned, instead.
Example Python usage:
value = frame0.WatchValue('global',
lldb.eValueTypeVariableGlobal,
lldb.LLDB_WATCH_TYPE_READ|lldb.LLDB_WATCH_TYPE_WRITE)
Add TestSetWatchpoint.py to exercise this API.
We have 400 test cases now.
llvm-svn: 140436