Resolver needs bind to src IP option

[grarpamp]

I looked through these pages and did not see
an option to bind the resolver query from a specific
IP address (as in the case where you have multiple
interfaces and/or alias addresses and wish to pick
one instead of the default route).

resolver(3)
gethostbyname(3)
resolver(5) [resolv.conf]

You could steer them with NAT filter, or bind a local
unbound/named to a src IP and point the resolver at that.
But those seem heavier weight solutions than
doing it in the resolver natively (whether in resolv.conf
or in library calls by applications [where in the apps case,
resolv.conf would decide whether application call or
resolv.conf takes precedence]).

Thoughts?