gawk allows multiple arguemnts to bit-wiste and, or and xor
functions. Implement an arbitrary number of arguments for these
functions. Also, use NULL in preference to 0 to match rest of file.
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D12361
As discussed during AsiaBSDcon devsummit, import the manpage from OpenBSD which
is has been rewritten in mdoc(7) format making it readable by default with
mandoc, it also has been extended by OpenBSD to cover all awk(1) options
Obtained from: OpenBSD
MFH: 1 week
