Though configure is derived from configure.in but requires autoconf
to build.  Some folks may not have autoconf installed.

Now to sort out configure enable/with options.

Added NO_THREAD support to configure.in.  (Still need thread lib detection)

however much is still needed (included db2 and thread detection)

handle ldapconfig.h.in.

completed handling of options yet.

Remove include/portable.h as it will now be built by configure.