games/ioquake3-devel: Remove in favour of ioquake3

Upstream requested us to point games/ioquake3 to github master,
making this port obsolete.

PR: 217911
Reviewed by: miwi
Approved by: miwi (mentor)
MFH: 2017Q2
Security: CVE-2017-6903
Security: e48355d7-1548-11e7-8611-0090f5f2f347
Differential Revision: https://reviews.freebsd.org/D10172