* configure.in: Many changes to support the rewriting of the utmp

	* configure.in: Many changes to support the rewriting of the utmp
	pieces of libpty.  Do a large amount of checking for consistency
	of various utmp and utmpx APIs as currently understood.  See rant
	in update_utmp.c.

	* dump-utmp.c: Rewrite; now has capability to use utmp{,x}name()
	to extract entries from utmp and utmpx files.  Adjusts field
	widths when printing as appropriate.

	* libpty.h: Update call signature for update_utmp() and logwtmp();
	make prototypes unconditional.

	* logwtmp.c: Rewrite.  Use pututline() or pututxline() API
	whenever possible.

	* pty-int.h: Update call signatures for update_wtmp{,x}(); make
	prototypes unconditional.

	* sane_hostname.c: Use the autoconf-correct macro names.

	* update_utmp.c: Rewrite.  Basically, use functions from the
	pututline() or pututxline() API whenever possible, to avoid
	lossage.  Inserted large rant about the conjectured history of BSD
	utmp, sysV utmp, and utmpx, as well as documentation about some
	known quirks.

	* update_wtmp.c: Rewrite.  Add new function ptyint_logwtmpx() that
	takes a utmpx rather than a utmp, so it can fail to lose data
	converting to and from utmp.

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@13218 dc483132-0cff-0310-8789-dd5450dbe970