This adds support for a plugin that can be attached to a vhost
to acquire and maintain its TLS cert automatically.
It works the same with both OpenSSL and mbedTLS backends, but
they can't share auth keys, delete the 'auth.jwk' file as it is
in the example JSON when switching between libs
- Add platform helpers for pipe creation.
- Change the direct-to-fds implementation to create a wsi for each
pt and use the normal apis to bind it to the event loop.
- Modifiy context creation and destroy to create and remove the
event pipe wsis.
- Create the event pipe wsis during context create if using the
default poll() event loop, or when the other event loops start
otherwise.
- Add handler that calls back user code with
LWS_CALLBACK_EVENT_WAIT_CANCELLED
This patch allows you to call `lws_cancel_service(struct lws_context *context)`
from another thread.
It's very cheap for the other thread to call and is safe without
locking.
Every use protocol receives a LWS_CALLBACK_EVENT_WAIT_CANCELLED from
the main thread serialized normally in the event loop.
