<rdar://problem/13527167>

Partial fix for the above radar.

Call ThreadList::Clear() in the ThreadList destructor so if any other threads currently have the thread list mutex, we won't destroy the list for them while they are using it. ThreadList::Clear() takes the mutex and clears the thread list contents.



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@178257 91177308-0d34-0410-b5e6-96231b3b80d8
Be sure to take the mutex when the destructor is called in case other threads are using these lists and those other threads have the mutex locked.



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@178262 91177308-0d34-0410-b5e6-96231b3b80d8
Hardening the vector iterator synthetic child(ren) provider against item-not-in-cluster asserts

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@178265 91177308-0d34-0410-b5e6-96231b3b80d8