llgs: implement qThreadStopInfo.

This change implements this ticket:
http://llvm.org/bugs/show_bug.cgi?id=20899

Adds the qThreadStopInfo RSP command for llgs and includes a test that
verifies both debugserver and llgs respond with something reasonable
on a multithreaded app.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@217549 91177308-0d34-0410-b5e6-96231b3b80d8
Rework how resetting breakpoints in changed modules works.  Try to match up old
locations with new ones if possible.

Next up some test cases...


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@217551 91177308-0d34-0410-b5e6-96231b3b80d8