cray/basil, read mysql creds from /root/.my.conf

The /root/.my.cnf would typically contain the login credentials for
root.  If those are needed for Slurm, then it should be checking
that directory.

(In reply to Nina Suvanphim from comment #0)
...
> const char *default_conf_paths[] = {
> "/root/.my.cnf", <<<<<<<<<<<<<<<<<------- add this line
> "/etc/my.cnf", "/etc/opt/cray/MySQL/my.cnf",
> "/etc/mysql/my.cnf", NULL };

I'll also note that typically the $HOME/.my.cnf file would be
checked last rather than first.