Make path to ld preload library absolute so wswrapper works even if
path is changed before main program is executed (i.e. by the vncserver
wrapper script).
bind() was using the return value for the port number, but it's
actually the original port number that we should interpose on in the
bind() routine.
wswrapper.so will only interpose on the listen port specified in
WSWRAP_PORT.
Add simple wswrap script that sets the WSWRAP_PORT, LD_PRELOAD and
invokes the command line to wrap.