* syscalls.cc (stat_worker): Make global. Accept path_conv parameter for

* syscalls.cc (stat_worker): Make global.  Accept path_conv parameter for
passing information back to caller.
* winsup.h: Declare stat_worker.
* dir.cc (opendir): Use stat_worker rather than stat and pass path_conv
parameter to stat_worker for later inspection.
* syslog.cc (syslog): Teach syslog about syslog priorities other than LOG_ERR,
LOG_WARNING and LOG_INFO
* path.cc (path_conv::check): Don't perform file system or rootdir checks on
devices.