WLog, Transport, Gateway, Time

WLog:
* Add WLOG_PREFIX environment variable
* Add WLOG_FILTER environment variable
* Add support for pid, tid, and time in prefix

Time:
* Stubs in libwinpr-timezone, libwinpr-sysinfo
* Implement GetSystemTime, GetLocalTime

Gateway:
* Add /gateway-usage-method command line option
* Fix timeout for GatewayBypassLocal direct connection

Transport:
* Fix VerifyX509Certificate for direct versus gateway connection identification
* Add locks to prevent race condition in BIOs when used in full duplex mode