quartz: add mountain lion as version 8 to enum GdkOSXVersion

Also use GDK_OSX_UNSUPPORTED instead of 0 in gdk_quartz_osx_version().

gdk/quartz/gdkglobals-quartz.c

@@ -30,9 +30,9 @@ GdkWindow *_gdk_root = NULL;
 GdkOSXVersion
 gdk_quartz_osx_version (void)
 {
-  static gint32 minor = 0;
+  static gint32 minor = GDK_OSX_UNSUPPORTED;
 
-  if (!minor)
+  if (minor == GDK_OSX_UNSUPPORTED)
     {
       OSErr err = Gestalt (gestaltSystemVersionMinor, (SInt32*)&minor);
 

gdk/quartz/gdkquartz.h

@@ -47,7 +47,8 @@ typedef enum
   GDK_OSX_LEOPARD = 5,
   GDK_OSX_SNOW_LEOPARD = 6,
   GDK_OSX_LION = 7,
-  GDK_OSX_CURRENT = 7,
+  GDK_OSX_MOUNTAIN_LION = 8,
+  GDK_OSX_CURRENT = 8,
   GDK_OSX_NEW = 99
 } GdkOSXVersion;