This will be used to tag binaries that require W+X mappings.
I prefer that we tag the binaries with statements of fact (this binary makes W+X mappings) rather than demand policy decisions (turn off W^X mode), although for all existing cases it's not easy to succinctly state the fact. The other argument for wxneeded is that this is what the flag is already called by OpenBSD, and supported by lld there (as -z wxneeded). I'm also not sure the disable form (i.e., NT_FREEBSD_FCTL_DISABLE_WXORX) is more clear.
However this sort of discussion is the reason I posted it for review first, let's see what folks think.