The configure script parses the value of $X_LIBS when looking at the
--enable-x11-shared, which is getting set on Ubuntu 5.10 to "-L/usr/X11R6/lib"
... however, Ubuntu stores all the Xlib stuff in /usr/lib.

The end result in SDL is that the dynamic X11 stuff gets disabled by default,
unless you override like this:

 ./configure --x-libraries=/usr/lib

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%401573