user32: Send a WM_MOUSELEAVE even if another window calls TrackMouseEvent before the timer proc is called.

protseq to avoid taking the process-wide server_cs in the hot path for
each protocol.

rpcrt4: Abstract out the way incoming connections are waited for so that we no longer need to wait on Win32 handles.

the functions operate on an RpcConnection object, not an
RpcServerProtseq object.