watmath.1776: uuxqt bug fix

[utzoo!decvax!duke!ucf-cs!whm]

Watmath!dmmartindale didn't mention why to add the fclose(xfp), but
before we added that on our system, uuxqt would stop after running
every 16 X files, and have to be restarted.

The bug causes files to be left open and causes all sorts of trouble
in programs that uuxqt starts up.  The most notable problem that we
had with this was that rmail (actually delivermail) would die with
a rc of 17192, and drop the incoming letter in the process.