munin: automatic configuration fails due to missing directory

[raimue (Rainer Müller)]

1. The initial configuration of munin fails due to the missing directory plugin-conf.d with the following error message:

Could not open plugin configuration directory: No such file or directory at /opt/local/lib/perl5/site_perl/5.12.4/Munin/Node/Service.pm line 81

The attached patch adds this directory to destroot.keepdirs, so it is no longer automatically deleted.

2. The automatic detection also needs to be run as the user munin as otherwise all plugins will fail in the autoconf step. Munin tries to be clever and drop the superuser privileges, but that does not work with setrgid here:

Plugin 'munin_stats' Can't drop privileges: setrgid() not implemented at /opt/local/lib/perl5/site_perl/5.12.4/Munin/Node/OS.pm line 261.

Therefore, use sudo -u munin for the automatic configuration.

3. Additionally, the default configuration files should be installed with a .sample extension and copied if they do not exist yet.

[raimue (Rainer Müller)]

Maintainer timeout, committed in r101939.