Minor makesock() fixes.

Minor makesock() fixes.

On getaddrinfo() or setsockopt() errors, we leak the flowopts and/or
the local/remote address info structure. Fix this by jumping to the
cleanup section at the bottom of makesock() rather than returning
early without cleaning up.

Moreover, we can not rely on errno containing a valid error code in the
cleanup part of the function because flowopt_cleanup() calls free()
which usually resets errno. So use the error code provided via "rc"
if possible and fall back to the new -E_MAKESOCK if rc is non-negative
to make sure we return a negative value on errors.