x11-servers/xwayland-devel: drop -displayfd workaround after 3312d027696f

Restore -nolock when using -displayfd for consistency with Xorg and Linux.
Now prints a benign warning for every used display e.g.,

$ for dpy in :0 :1 :2 :3; do daemon -f Xwayland $dpy; done
$ Xwayland -displayfd 1
_XSERVTransSocketUNIXCreateListener: ...SocketCreateListener() failed
_XSERVTransMakeAllCOTSServerListeners: server already running
_XSERVTransSocketUNIXCreateListener: ...SocketCreateListener() failed
_XSERVTransMakeAllCOTSServerListeners: server already running
_XSERVTransSocketUNIXCreateListener: ...SocketCreateListener() failed
_XSERVTransMakeAllCOTSServerListeners: server already running
_XSERVTransSocketUNIXCreateListener: ...SocketCreateListener() failed
_XSERVTransMakeAllCOTSServerListeners: server already running
4
[...]

See also https://lists.freedesktop.org/archives/xorg-devel/2015-March/045899.html
wlroots, kwin_wayland, mutter already create /tmp/.X*-lock files.

This reverts commit fb41bd9ef0438118ccc7e2e43d952fc8c2adcd63.