cad/alliance: Update to 5.1.1, remove BROKEN and undeprecate

• The code has been modernized so most of the patches and the workaround with USE_CXXSTD are therefore no longer required. USE_GCC is still needed for build as some files cannot be compiled with Clang.
  
  The updated code also contains no more occurences of the long deprecated gets(3) function which has been removed since FreeBSD 1300043. [1]

• A patch from Debian's patchset [2] is required to remedy build issues with the documentation.

• Add USE_XORG to pass stage QA as some binaries are linked against various X libraries. Among these libraries is also the recently deprecated x11/libXp, which is probably not needed but (still) pulled in by the OpenMotif toolkit.

• Also pet portlint/portclippy while I'm here by grouping related USE_* variables to the USES block and sort the other variables according to the PHB.

PR: 238686
Submitted by: Loïc Bartoletti <lbartoletti@tuxfamily.org> (based on)
Reported by: emaste [1]
Obtained from: Debian [2]