- Remove codes related to WITH_BDB6_PERMITTED from Mk/Uses/bdb.mk. Currently user needs to set 'WITH_BDB6_PERMITTED=yes'in /etc/make.conf to use db18 as default version of BDB. The variable is introduced for user who doesn't want to accept AGPLv3 when upstream changed license with the release of 6.0. However, after db5 is removed it becomes meaningless as db18 is the only available version of BDB. Moreover it makes it impossible to change default version BDB to 18. So remove them.
- Remove compatiblity hack to upgrade older plussed versions to 5+ as there isn't such case in ports tree anymore.
- Remove INVALID_BDB_VER and replace it with argument of 'USE=bsb'.
- Stop checking if there is already installed version of berkeley db. While testing migration from db5 to db18, I found following confuging situation. (1) Currently default version of bdb is 5. So if a port uses 'USES=bdb', then install packages depends of db5. (2) To migrate to db18, add 'DEFAULT_VERSIONS+=bdb=18' to /etc/make.conf. (3) Rebuild package installed at (1). (4) Now it is expected the package depends on db18. But what really happens is that it still depends on db5. It happens because when db5 is already installed it is used as default version of bdb even if there is 'DEFAULT_VERSIONS+=bdb=18' in /etc/make.conf. It's against user's expectation. So remove the logic.
PR: 261523