Remove X11 requirement from Autotools.
@@ -6,6 +6,6 @@ includedir=@includedir@
Name: libtcod
Description: A roguelike development library.
Version: @PACKAGE_VERSION@
-Requires.private: sdl2 >= 2.0.5, x11, zlib
+Requires.private: sdl2 >= 2.0.5, zlib
Cflags: -I${includedir}
Libs: -L${libdir} -ltcod
