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)

Const poisoning.

Add __FBSDID()s to libutil

Fix problems people were having with large -O levels with GCC and
getting libutil/libcrypt to work properly. I've determined that GCC
thinks it can inline all functions, including weak-symboled ones, if
it feels like it.

Create a new stub.c and move any stubs there to prevent inlining.
Thanks to jdp and William S. Duncanson for helping me finally find the
problem.

Add weak symbol pragma for crypt_set_format().

Approved by: green

Stick login_setcryptfmt() in its own file to make pulling in of
-lcrypt only happen if truly necessary.