xterm-color256: Different behavior between NetBSD 9.2 and 9.99.93?

[Matthias Petermann <mp%petermann-it.de@localhost>]

Hello all,

on my NetBSD systems I set the environment variable TERM to 
"xterm-color256". This makes console apps like mc, taskwarrior, fish, 
micro etc. more attractive as it allows the use of 256 color themes. At 
least this is the case in NetBSD 9.2.

On NetBSD 9.99.93 (build from 01/22/2022), however, only a 8-color 
terminal is recognized by mc, for example, despite the TERM variable 
being set. I could also check this with tput:

NetBSD 9.2:

```
$ echo $TERM
xterm-256color
$ tput colors
256
```

NetBSD 9.99.93:

```
$ echo $TERM
xterm-256color
$ tput colors
8
```

Were there changes here that require a different type of configuration, 
or is this a bug?

Kind regards
Matthias