BUG/MEDIUM: cache: don't cache the response on no-cache="set-cookie"

BUG/MEDIUM: cache: don't cache the response on no-cache="set-cookie"

If the server mentions no-cache="set-cookie" in the response headers,
we must guarantee that any set-cookie field will not be stored. We
cannot edit the stored response on the fly to trim the set-cookie
header so we can refrain from storing a response containing such a
header. In theory we could use TX_SCK_PRESENT for this but this one
is only set when the cookie is being watched by the configuration.
Since these responses are not very frequent and often accompanied
with a set-cookie header, let's simply refrain from caching whenever
such directive is present.

This needs to be backported to 1.8.