wadinfo-builder.pl: change license to BSD
wadinfo-builder.pl: change license to BSD

<fraggle> feel free to replace the comment with a bsd license header
          then
<fraggle> it's fine by me

Signed-off-by: Mike Swanson <517655fde76fa2f07143b6c6f1774e4fae45930a@gmail.com>

jmtd/freedoom,CWolfRU/freedoom,jmtd/freedoom,CWolfRU/freedoom,jmtd/freedoom