Enhanced the ObjC DynamicCheckerFunction to test for "object responds to selector" as well as
"object borked"...  Also made the error when the checker fails reflect this fact rather than
report a crash at 0x0.

Also a little cleanup:
- StopInfoMachException had a redundant copy of the description string.
- ThreadPlanCallFunction had a redundant copy of the thread, and had a 
copy of the process that it didn't really need.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@143419 91177308-0d34-0410-b5e6-96231b3b80d8
11 files changed