Fix Skype Not Working In Ubuntu 13.04 Raring Ringtail [For Users With Proprietary Nvidia Or AMD Drivers]

Some Ubuntu 13.04 Raring Ringtail users are having issues with Skype not starting when using the proprietary Nvidia graphics drivers (it crashes / segfaults). So here's a work-around you can use to get it to work until this is fixed in Ubuntu / Skype.

Update: some users have confirmed that this fix also works if you're using proprietary AMD / ATI drivers.