Host: correct use of std::condition_variable::wait_for
Host: correct use of std::condition_variable::wait_for

std::condition::wait_for takes a std::unique_lock<T>.  The previous commit
accidentally left a reference to `m_mutex` instead of `lock`.  Update that.
Should restore the android lldb builder to green.

git-svn-id: 4c4cc70b1ef44ba2b7963015e681894188cea27e@277013 91177308-0d34-0410-b5e6-96231b3b80d8

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