Use upstream's version of our patch to set the default browser
    
    When setting the default browser, we want to set it to 'firefox %s'
    instead of '/usr/lib{,64}/firefox-4/firefox %s'
    
    firefox-default.patch did the job for us for a bit, but upstream now
    has a patch to do this which we can now use.  The patch will check
    to see if MOZ_APP_LAUNCHER is passed, and if so, it will use only
    the basename when setting the default browser.  We already set
    MOZ_APP_LAUNCHER, so just need to switch to using the patch.
    
    From https://bugzilla.mozilla.org/show_bug.cgi?id=611953
    Patch 1 - Use MOZ_APP_LAUNCHER for default browser executable (v3, un-bitrotted)