graphics/libepoxy: update to 1.5.10

Changes:    https://github.com/anholt/libepoxy/releases/tag/1.5.10
Reviewed by:	diizzy, jbeich
Tested by:	arrowd
Pull Request:	https://github.com/freebsd/freebsd-ports/pull/273
Sponsored by:   Serenity Cybersecurity, LLC