Update to XQuartz 2.7.6

## Summary
Apple [released XQuartz 2.7.6 on 2014.05.17](http://xquartz.macosforge.org/trac/wiki/X112.7.6). In addition to updating several library dependencies XQuartz 2.7.6 addresses several CVE's the worst of which may allow remote attackers to cause a denial of service (crash) and possibly execute arbitrary code.

## CVE's
- [CVE-2014-2240](http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-2240)
- [CVE-2013-6462](http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-6462)
- [CVE-2014-0209](http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-0209)
- [CVE-2014-0210](http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-0210)
- [CVE-2014-0211](http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-0211)