update net/guacamole-server to 0.9.10

Changelog: https://github.com/apache/incubator-guacamole-server/commits/0.9.10-incubating

• Updated to 0.9.10
• Changed LICENSE to APACHE20
• New option GUACENC: Video Encoding Utility

PR: 216350
Submitted by: ultima1252@gmail.com (maintainer)
Reviewed by: matthew
Approved by: matthew (mentor)
Differential Revision: https://reviews.freebsd.org/D9281