regress_bufferevent: add TT_IOCP_LEGACY/TT_IOCP

t/bench_http: disable buffering (win32 do not show anything otherwise)

s/http-server: check for EVTHREAD_USE_WINDOWS_THREADS_IMPLEMENTED

Merge branch 'iocp-fixes'

regress: test for HTTP/HTTPS with IOCP enabled

bev_async: trigger/run only deferred callbacks

bev_async: do not initialize timeouts multiple times

bev_async: set "ok" on setfd if fd>=0 (like we do during creation)

bev_async: ignore ERROR_INVALID_PARAMETER on .setfd for iocp

Fix conceivable UAF of the bufferevent in evhttp_connection_free()

Use BEV_UPCASE() everywhere

regress: add EVENT_NO_FILE_BUFFERING, to disable buffering for stdout/stderr

event: add some debug information into loop for event_base_free_queues_()

Merge branch 'sample-http-server'

s/http-server: graceful cleanup