Apple supports anything here that Clang supports and should have them
set the same as everywhere else.
Most importantly this gives apple the -Wno-deprecated-declarations flag
which has been driving me nuts on macos.
This also version-gates the -Wno-deprecated-declarations so that it
will turn on again when we bump the version beyond .10.
Adds support for building Lokinet as a system extension, and fixes
various problems in the macos implementation found during development of
the system extension support.
When we enable/disable exit mode on this restarts the unbound DNS
responder with the DNS trampoline (or restores upstream, when disabling)
to properly route DNS requests through the tunnel (because libunbound's
direct requests don't get tunneled because unbound is inside the network
extension).
This runs a DNS listener on localhost:1053 that bounces requests to the
upstream DNS through the tunnel. The idea here is that, when we turn on
exit mode, we start libunbound bouncing the requests through the
trampoline (since if it makes direct requests they won't go through the
tunnel).
(The actual libunbound configuration is still to follow).
