Add thread-id field in *stopped notification (MI)

Summary:
Add thread-id field in *stopped notification (MI) + tests

All tests pass on OS X

Reviewers: zturner, clayborg, abidh

Reviewed By: clayborg

Subscribers: lldb-commits, zturner, clayborg, abidh

Differential Revision: http://reviews.llvm.org/D7501

llvm-svn: 228681