VERSION 4.0.3: fix make test

See cirrys.yml how to setup /linuxid*

VERSION 4.0.2: fixed make musl

Debian Trixie showed issues when using _GNU_SOURCE.
Hence this was replaced by _DEFAULT_SOURCE.

VERSION 4.0.0: security fix and breaking change

THIS MAY BREAK COMMANDS which require secondary groups.
In that case, add Flag 'K' to get the old behavior.

fixes #26 leak of groups

Without flag K all secondary groups are cleared.
This was the behavior until version 3.3.

Note: If you switch back to the calling user and need all
secondary groups intact, be sure to add 'K' to the flags!

As always, security first means, to always apply max. sec
without flags.

suid_version.h modified