media-tv/tvheadend: Version bump to 4.2.4 and 9999 update

media-tv/tvheadend: Version bump to 4.2.4 and 9999 update

* Add support for dvbcsa via USE flag
* Add support for dvben50221 via USE flag
* Drop support for libav (fails version checks, missing symbols)
* Source DTV scan tables from new media-tv/dtv-scan-tables package
* Set tvheadend user HOME to /etc/tvheadend to allow for XMLTV data
* Tighten up the systemd service unit
* Add debug USE flag for trace support
* Fix inotify kernel config check
* Add ffmpeg sub-dependencies and associated USE flags (9999 only)

Closes: https://bugs.gentoo.org/579048
Closes: https://bugs.gentoo.org/579986
Closes: https://bugs.gentoo.org/586448
Closes: https://bugs.gentoo.org/588210
Closes: https://bugs.gentoo.org/626238
Package-Manager: Portage-2.3.16, Repoman-2.3.6