Handle old style S packet correctly

    
    SUMMARY:
    This patch fixes couple of issues:
    1. A thread tries to lock a mutex which is already locked.
    2. Updating a thread list before the stop packet is parsed so that it can get a valid thread id and allows to set the stop info correctly.
    
    Reviewers: clayborg
    Subscribers: mohit.bhakkad, sagar, jaydeep, lldb-commits
    Differential Revision: http://reviews.llvm.org/D11449

llvm-svn: 243091