673b3d8dbd
With https://github.com/tailscale/corp/commit/a42a594bb311686197b64d6389524920a2b07b2a, iOS uses netstack and hence there are no longer any platforms which use the legacy MagicDNS path. As such, we remove it. We also normalize the limit for max in-flight DNS queries on iOS (it was 64, now its 256 as per other platforms). It was 64 for the sake of being cautious about memory, but now we have 50Mb (iOS-15 and greater) instead of 15Mb so we have the spare headroom. Signed-off-by: Tom DNetto <tom@tailscale.com>