When using http/1.1+ keepalive and mounts, the relationship between
a connection and a protocol becomes dynamic. The same connection might
visit different bits of the url space served by different mounts using
different protocols.
This patch ensures protocols can cleanly manage their per-connection
allocations by using the following callbacks when the protocol changes
LWS_CALLBACK_HTTP_BIND_PROTOCOL
LWS_CALLBACK_HTTP_DROP_PROTOCOL
For example if the pss wants to malloc stuff at runtime, it should do it
in LWS_CALLBACK_HTTP_BIND_PROTOCOL or later, and clean it up in
...DROP_PROTOCOL.
Signed-off-by: Andy Green <andy@warmcat.com>