ASCII Art: initialize Xlib

Don't ask me why, but libaa depends on Xlib.
(cherry picked from commit d6d738ce)

configure.ac

@@ -3729,6 +3729,9 @@ then
   then
     VLC_ADD_PLUGIN([aa])
     VLC_ADD_LIBS([aa],[-laa])
+    if test "${SYS}" != "mingw32"; then
+      VLC_ADD_LIBS([aa],[${X_LIBS} ${X_PRE_LIBS} -lX11])
+    fi
   fi
 fi
 

modules/video_output/aa.c

@@ -37,6 +37,13 @@
 #include <assert.h>
 #include <aalib.h>
 
+#ifndef WIN32
+# ifdef X_DISPLAY_MISSING
+#  error Xlib required due to XInitThreads
+# endif
+# include <vlc_xlib.h>
+#endif
+
 /* TODO
  * - what about RGB palette ?
  */
@@ -85,6 +92,11 @@ static int Open(vlc_object_t *object)
     vout_display_t *vd = (vout_display_t *)object;
     vout_display_sys_t *sys;
 
+#ifndef WIN32
+    if (!vlc_xlib_init (object))
+        return VLC_EGENERIC;
+#endif
+
     /* Allocate structure */
     vd->sys = sys = calloc(1, sizeof(*sys));
     if (!sys)