The code to determine the socket address of chansrv when using
a manually started xrdp-chansrv may need some help determining
the UID of the session.
This commit allows a UID to be optionally specified in the
DISPLAY() function, if the code is unable to determine the
UID automatically from the connection parameters.
If a manual chansrvport is entered, xrdp now logs what it is
connecting to, to assist in debugging.
d17d12d078