Reserve UID/GID where only one exists

[feld]

Summary

UIDs and GIDs files are getting full. I have identified instances where
a port did not require both a UID and a GID, so the committer only
created one entry. As a result, it makes it significantly more difficult
to identify which UIDs and GIDs are "free" and if future updates of the
software warrant the usage of a UID or GID it will become messy as the
matching ID may not be available.

This diff creates groups where only a user existed and creates
"reserved" users where only the group existed.

[mat]

I strongly disagree, some ports only need a group so that more tha one person can touch their config file but have no use for a user.

GIDs

36–40

I think @bdrewery can tell a bit more about this, but I do think it is useless, all qmail software run with the same group.

[feld]

GIDs

69

My mistake, this is the entry that should be added regardless... UIDs file has hplip user with 116 as default group, but that group didn't exist. (port should probably be updated to use GROUPS too)

[feld]

general agreement was that UID/GID matching/reservations are unnecessary