Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Revert r224760, and enhance the sed patterns from r224659 to comment out
the _compat entries in the WITHOUT_NIS case rather then delete them.

Approved by: re (kib)

Rather than edit the nsswitch.conf file based on ${MK_NIS} == "no"
comment out the NIS _compat options by default, but leave them in
the file for the convenience of users who want to enable it.

Update the comment in the file accordingly.

Reviewed by: ed
Approved by: re (hrs)

Install /etc/nsswitch.conf statically rather than generating it at
boot. Autogeneration of nsswitch.conf doesn't makes sense in 7.0
since it's not permitted to upgrade from a pre-nss release without
passing through an intermediate release.

Suggested by: brooks