bugs: fixes for 64-bit windows build
webdav_server: remove abort() from common code paths in handle_lock_request and handle_delete_request
webdav_server: don't send the http content-length header when responding with the 204 (no-content) status code
logging: grab mutex lock when doing log output
http_server/webdav_server: overhaul logging during requests, make sure to print request identifier
fstatat_emu: make fstatat_x thread-safe and only use under the strictest of conditions, i.e. don't allow external (f)chdir() calls

--HG--
extra : amend_source : f2f167f70b93c98d92d244098307859ad5965480
http_server: http_server doesn't own the listen socket it is passed, so it's not responsible for closing it