"declare" apparently isn't a valid keyword; use typedef instead.

These changes came from the versions of those files at the tip of the
Samba trunk, and fix the failures to compile with pidl.

Change-Id: Ifc3276d4bc2ff1cfdb19819811f5b8d1b91961b5
Reviewed-on: https://code.wireshark.org/review/4329
Reviewed-by: Guy Harris <guy@alum.mit.edu>