GCC 9.0 is complaining because we're trying to print strings that
are defined like this:
.zo_pool = { 'z', 't', 'e', 's', 't', '\0' },
Fix them by making them actual strings.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes#8330
caacc6e4c4