fix missing X11 library in some cases

configure.ac

@@ -298,7 +298,9 @@ AC_ARG_ENABLE(x11,
 if test "$video" = "true"; then
 	
 	if test "$enable_x11" = "true"; then
-	   AC_CHECK_HEADERS(X11/Xlib.h)
+	  	AC_CHECK_HEADERS(X11/Xlib.h)
+		AC_CHECK_LIB(X11,XUnmapWindow, X11_LIBS="-lX11")
+		AC_SUBST(X11_LIBS)
 	fi
 	AC_DEFINE(VIDEO_ENABLED,1,[defined if video support is available])
 fi

console/Makefile.am

@@ -23,7 +23,8 @@ linphonec_LDADD = $(top_builddir)/coreapi/liblinphone.la $(READLINE_LIBS)  \
 		$(MEDIASTREAMER_LIBS) \
 		$(ORTP_LIBS) \
 		$(SPEEX_LIBS) \
-		$(OSIP_LIBS)
+		$(OSIP_LIBS) \
+		$(X11_LIBS)
 
 if BUILD_WIN32
 #special build of linphonec to detach from the windows console