<rdar://problem/13527167>
<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: 4c4cc70b1ef44ba2b7963015e681894188cea27e@178257 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,llvm-mirror/lldb,llvm-mirror/lldb,apple/swift-lldb,llvm-mirror/lldb,llvm-mirror/lldb,apple/swift-lldb,llvm-mirror/lldb