Fix assignment written as a comparison in validate_arguments() when db_pass is NULL (Patch from http://blog.barfoo.org/projects/rpms-for-sles10)
git-svn-id: https://nagiosplug.svn.sourceforge.net/svnroot/nagiosplug/nagiosplug/trunk@2034 f882894a-f735-0410-b71e-b25c423dba1c