Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

style.Makefile(5) police
(I've tried to keep to the spirit of the original formatting)

Reviewed by: des

Moved SHLIB_NAME definition into one place.

Approved by: des

Switch to OpenPAM. Bump library version. Modules are now versioned, so
applications linked with Linux-PAM will still work.
Remove pam_get_pass(); OpenPAM has pam_get_authtok().
Remove pam_prompt(); OpenPAM has pam_{,v}{error,info,prompt}().
Remove pam_set_item(3) man page as OpenPAM has its own.

Sponsored by: DARPA, NAI Labs

Add a pam_self authentication module that succeeds if and only if the local
and remote user names are the same.

Sponsored by: DARPA, NAI Labs