Add an "Avoid Frames matching this regular expression" to ThreadPlanStepInRange.

This relies on ThreadPlanStepOut working correctly, which it doesn't currently for Inlined functions, so this feature is only partially useful until we take care of Stepping Out of inlined functions.
Added an option to "thread step-in" to set the avoid regular expression.  This is mostly for testing, once the Setting code is redone, we'll move this to a general setting.

llvm-svn: 108036