Linux's syslog is a local socket, so this uses the recent UDS work.
* Most of redox.rs is refactored into mod.rs now which has all of the C
facing functions and consts.
* I wrapped the global logger in a Mutex instead of a RwLock. The logger
is almost always locked for writing so a Mutex is simpler as RwLock
provides no benefits.
* I implemented LOG_PERROR which also prints errors to stderr as well as
the log.
* Syslog should be sys/syslog.h with syslog.h as an alias (the
original code only had syslog.h).
Josh Megnauth