A little cleanup. {Disable/Enable}Breakpoint actually disables/enables...

A little cleanup.  {Disable/Enable}Breakpoint actually disables/enables BreakpointSites not breakpoints, it is confusing
to have it not named appropriately.  Also in StopInfoMachException, we aren't testing for software or not software, just
whether the thing is a breakpoint we set.  So don't use "software"...

llvm-svn: 175241