[crossfire] GTK client compilation issue w/ newer autotools

[David McIlwraith]

Hi,

X_LIBS does not appear to include libX11 with bleeding-edge auto*
tools; I am not sure if this is an issue with the client source itself
or a problem elsewhere. Nonetheless, on svn r16896 (up-to-date local
ArchLinux [x86_64] system), configure.ac must be modified such that
-lX11 is added in a similar vein to Xext. Noting that I have not
encountered this issue before when packaging the client, I am unsure
as to where the problem lies -- does anyone have any insight here?

Regards,
- David McIlwraith <2c93e8f1 at gmail.com>