Set correct ThreadStopInfo in case of trace event

Summary:
 - The patch solves Bug 23478 and Bug 19311. Resolving
   Bug 23478 also resolves Bug 23039.
      Correct ThreadStopInfo is set for Linux and FreeBSD
      platforms.

 - Summary:
      When a trace event is reported, we need to check
      whether the trace event lands at a breakpoint site.

      If it lands at a breakpoint site then set the thread's
      StopInfo with the reason 'breakpoint'. Else, set the reason
      to be 'Trace'.

Change-Id: I0af9765e782fd74bc0cead41548486009f8abb87
Signed-off-by: Abhishek Aggarwal <abhishek.a.aggarwal@intel.com>

Reviewers: jingham, emaste, lldb-commits, clayborg, ovyalov

Subscribers: emaste

Differential Revision: http://reviews.llvm.org/D16720

llvm-svn: 259344