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. 
* A patch from Debian's patchset  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
* 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
Submitted by: Loic Bartoletti <email@example.com> (based on)
Reported by: emaste 
Obtained from: Debian