Since the AES code builds, and doesn't do any configure-time byte order checks

Since the AES code builds, and doesn't do any configure-time byte order checks
that I noticed, something similar ought to work for the DB code.  This is the
first cut; nightly testing builds should tell us if it's sufficient on most of
the platforms we work on.

* include/db-int.h: Include stdlib.h, and endian.h if available.
(LITTLE_ENDIAN, BIG_ENDIAN, BYTE_ORDER): If not defined, and if versions with
one or two leading underscores are defined, define the no-underscore form in
terms of the with-underscore one.
(DB_BYTE_ORDER): Define by checking LITTLE_ENDIAN, BIG_ENDIAN, and BYTE_ORDER;
report an error if that doesn't work.  Don't check WORDS_BIGENDIAN.

* Makefile.in (all-prerecurse): Make sure headers generated by config.status
are up to date.
(include/config.h, $(srcdir)/include/config.h.in, include/db-config.h): New
rules.
* configure.in: Don't check byte order here.  Check for endian.h.

ticket: 2551
status: open

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@16317 dc483132-0cff-0310-8789-dd5450dbe970