sysutils/screen: Update to 4.9.0

Update screen to 4.9.0. From the release announcement:

New in this release:

• Hardstatus option for used encoding (escape string '%e')
• Fixes:
  • fix combining char handling that could lead to a segfault
  • CVE-2021-26937: possible denial of service via a crafted UTF-8 character sequence (bug #60030)
  • make screen exit code be 0 when checking --help
  • session names limit is 80 symbols (bug #61534)
  • option -X ignores specified user in multiuser env (bug #37437)
  • a lot of reformations/fixes/cleanups (man page and source code)

For full list of changes see
https://git.savannah.gnu.org/cgit/screen.git/log/?h=v.4.9.0

Note that CVE-2021-26937 was fixed in the FreeBSD port in 2021.