Fix GCC buildbot failures in API/Multithreaded tests
- fix typo initializing unique_ptr
- add missing throw specifier to play nice with older libstdc++ exception class



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@181831 91177308-0d34-0410-b5e6-96231b3b80d8
Remove XFAIL from tests affected by llvm.org/pr-14637
- unable to repro locally, much like many people commenting on the issue



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@181833 91177308-0d34-0410-b5e6-96231b3b80d8