build: Make --with-json-audit the default

build: Make --with-json-audit the default

Thanks to Rowland for a clear description of the behaviour for the smb.conf manpage.

This means that those not wanting to link to libarchive will just need to
build --without-json-audit.

In general, we prefer that optional libraries be required by default
so that they are not accidentially missed, particularly in packages.

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>