Delete a directory, crash the system

[David Noel]

> Post the stack trace of the core and maybe someone can help you.

panic: ufs_dirrem: Bad link count 2 on parent
cpuid = 0
KDB: stack backtrace:
#0 0xffffffff808680fe at kdb_backtrace+0x5e
#1 0xffffffff80832cb7 at panic+0x187
#2 0xffffffff80a700e3 at ufs_rmdir+0x1c3
#3 0xffffffff80b7d484 at VOP_RMDIR_APV+0x34
#4 0xffffffff808ca32a at kern_rmdirat+0x21a
#5 0xffffffff80b17cf0 at amd64_syscall+0x450
#6 0xffffffff80b03427 at Xfast_syscall+0xf7