Remove check for X.

The game uses only SDL library. There is no need to check for X.

diff --git a/configure.in b/configure.in
index 2270cb4..f0a93c6 100644
--- a/configure.in
+++ b/configure.in
@@ -98,17 +98,6 @@ if test "x$is_win32" = "xyes" ; then
     TR_LIBS="$TR_LIBS -luser32 -lgdi32"
 fi
 
-dnl --------------------------------------------------------------------------
-dnl Check for X  
-dnl Note that we only need libs (so that glut links properly on all systems).
-dnl --------------------------------------------------------------------------
-if test "x$is_win32" = "xno" ; then
-    AC_PATH_XTRA
-    if test "x$no_x" = "x" ; then
-	TR_LIBS="$X_PRE_LIBS $X_LIBS -lX11 -lXi -lXext -lXmu -lXt $X_EXTRA_LIBS $TR_LIBS"
-    fi
-fi
-
 dnl --------------------------------------------------------------------------
 dnl Check for some common libraries
 dnl --------------------------------------------------------------------------
-- 
2.41.0