Import commit from NetBSD with checkin message:
Avoid Undefined Behavior in ffs_clusteracct() Change the type of 'bit' variable from int to unsigned int and use unsigned values consistently. sys/ufs/ffs/ffs_subr.c:336:10, shift exponent -1 is negative Detected with Kernel Undefined Behavior Sanitizer. Reported by <Harry Pantazis>
Submitted by: Pedro Giffuni