Adding any unknown option to the "[mysqld_safe]" section makes
mysqld impossible to start with mysqld_multi. For example, after
adding the unknown option "numa_interleave" to the "[mysqld_safe]"
section, mysqld_multi exits with the following diagnostics:

[ERROR] /usr/local/mysql/bin/mysqld: unknown option '--numa_interleave'

To get rid of this behavior, this patch adds the passing of the default
group suffix from mysqld_multi to the mysqld_safe side.