media-video/vdr: fix multiple QA issues

media-video/vdr: fix multiple QA issues

* QA issue: USE flag 'permashift_v1' uses reserved underscore
  character, rename USE flag 'permashift_v1' to 'permashift'
* QA issue: UnnecessarySlashStrip in DESTDIR="${D%/}"
* QA issue: makefile installs pre-compressed manpages

Bug: https://bugs.gentoo.org/695066
Closes: https://github.com/gentoo/gentoo/pull/13588
Package-Manager: Portage-2.3.78, Repoman-2.3.17
Signed-off-by: Martin Dummer <martin.dummer@gmx.net>
Signed-off-by: David Seifert <soap@gentoo.org>