games/doomlegacy: update Doom Legacy to version 1.48.18 (rev1749)
- HAVE_LIBZIP and HAVE_ZLIB are now set by default for *nix builds, adjust the port's Makefile accordingly
- Version 1.48.16 had been skipped due to a broken save game (corrupted) and the MBF21 support did not work right
Reported by: portscout