lib/parse_ini.c: Search for INI file in subdirs

Add two path names to the list of default INI file locations, as some
users/distributions prefer to put configuration files into
subdirectories.
plugins/runcmd.c: Remove superfluous newline

The puts(3) function already appends a newline character to the string.
Use FindBin consistently across Perl plugins

Use Perl's FindBin module to locate the path to utils.pm in
check_file_age.pl and check_mssql.pl, just as we do in other Perl
plugins.