Fix crash in QFontDialog::getFont() on Mac 10.4

[NSFontManager setTarget] is not available on 10.4.

Rev-by: Richard Moe Gustavsen

Author: Morten Johan Sørvig

src/gui/dialogs/qfontdialog_mac.mm

@@ -394,7 +394,9 @@ - (void)cleanUpAfterMyself
     }
     [mFontPanel setDelegate:nil];
     [[NSFontManager sharedFontManager] setDelegate:nil];
+#ifdef QT_MAC_USE_COCOA
     [[NSFontManager sharedFontManager] setTarget:nil];
+#endif
 }
 @end
 
@@ -518,7 +520,9 @@ and with buttons (OK and Cancel).
                                                    extraHeight:dialogExtraHeight];
     [ourPanel setDelegate:delegate];
     [[NSFontManager sharedFontManager] setDelegate:delegate];
+#ifdef QT_MAC_USE_COCOA
     [[NSFontManager sharedFontManager] setTarget:delegate];
+#endif
     setFont(delegate, initial);
 
     // hack to get correct initial layout