Add accessors on process to get & set the selected thread by IndexID (useful since that's the one that "thread list" shows and it won't get reused even if the underlying system thread ID gets reused.

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@160187 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed