Preserve one character space for a trailing '\0'.

Found by:	Ivan Klymenko via cppcheck
Discussed with: ae
MFC after:	1 week
In r260111, in sys/conf/files, I disabled warning about unused functions
for the wrong mcg.c, the one in ofed/drivers/infiniband/hw/mlx4.
Disable the warning for ofed/drivers/net/mlx4/mcg.c instead.

MFC after:	3 days
Disable warning about unused static const variables for sys/pci/ncr.c.

MFC after:	3 days