The NFS server modevent code manually patches the system call table to

The NFS server modevent code manually patches the system call table to
install nfssvc().  It also updates the argument count, but did so
without setting SYF_MPSAFE, effectively removing the MPSAFE flag even
when syscalls.master indicates it doesn't require Giant.  This change
forces the modevent to set MPSAFE as a flag to its internal notion of
an argument coutn.

Note: this duplication of information is a bad thing, but is a more
general problem I'm not currently willing to address.