add XBell to xlib. workaround for Leopard linking to X11 libGL

extra/x11/xlib/xlib.factor

@@ -1354,6 +1354,8 @@ FUNCTION: Bool XSupportsLocale ( ) ;
 
 FUNCTION: char* XSetLocaleModifiers ( char* modifier_list ) ;
 
+FUNCTION: int XBell ( Display* dpy, int percent ) ;
+
 SYMBOL: dpy
 SYMBOL: scr
 SYMBOL: root

vm/Config.macosx

@@ -6,7 +6,7 @@ PLAF_DLL_OBJS += vm/os-macosx.o vm/mach_signal.o
 DLL_EXTENSION = .dylib
 
 ifdef X11
-	LIBS = -lm -framework Foundation $(X11_UI_LIBS)
+	LIBS = -lm -framework Foundation $(X11_UI_LIBS) -Wl,-dylib_file,/System/Library/Frameworks/OpenGL.framework/Versions/A/Libraries/libGL.dylib:/System/Library/Frameworks/OpenGL.framework/Versions/A/Libraries/libGL.dylib
 else
     LIBS = -lm -framework Cocoa -framework AppKit
 endif