#200 [trousers] provide an option to skip user creation/deletion

[Alon Bar-Lev]

Hi,
At dist/Makefile.am a user is created/deleted, while there is NOUSERCHECK conditional, its scope is more than just skipping create/delete users.
Skipping these is important for downstream so that the user is created properly within distribution tools.
Please add another flag like --disable-usercheck, something like --disable-usermgt to skip these to help us drop the last remaining patch for this package.
Thanks!