net/asterisk18: Update to 18.12.0

• Embedded pjproject updated from 2.10 to 2.12
• Fix terminfo detection by adding the correct path to detection code [1]
• Add note to pkg-descr to explain that the misc/terminfo-db port is required to get color in the console
• Remove trailing whitespace

Reported by: ogogon@ogogon.org (via email) [1]