graphics/bugle: Lock it to GCC 7 and deprecate

It fails to build with GCC >= 8:

cc1: error: unrecognized command line option '-fdump-translation-unit'

http://package22.nyi.freebsd.org/data/112amd64-default-PR231590/2018-10-29_06h48m05s/logs/errors/bugle-0.0.20100508_12.log

The Changelog at [1] for newer versions says it's no longer developed,
so deprecate it as well:

"This is a bugfix release. BuGLe is no longer actively developed."

[1] https://sourceforge.net/projects/bugle/files/bugle/0.0.20150628/

PR: 231590