Done as a separate commit to make backporting the next patch easier.
We are already using "intprops.h", but this makes it explicit.

* .gnulib: Update, for syntax-check fix.
* bootstrap.conf (gnulib_modules): Make intprops use explicit.
* src/locking/domain_lock.c (includes): Drop unused header.
* src/nwfilter/nwfilter_learnipaddr.c (includes): Use "", not <>,
for gnulib.