games-fps/gzdoom: Bump to version 4.2.0

games-fps/gzdoom: Bump to version 4.2.0

The 'nonfree' USE flag is introduced to allow users to control whether
nonfree assets are installed.

Doom assets are under the Doom Collector's Edition license. Heretic and
Hexen assets are under the Activision license. Chex Quest assets are
under the Chex Quest 3 license. Strife assets are freely distributable
according to Stephen Kick, CEO of Nightdive Studios.

Closes: https://bugs.gentoo.org/692584
Package-Manager: Portage-2.3.73, Repoman-2.3.17
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Closes: https://github.com/gentoo/gentoo/pull/12833
Signed-off-by: James Le Cuirot <chewi@gentoo.org>