Header fixes:

* Do not include system headers in shared files (stdlib.h).
* Don't include lcd.h only once in each driver.
* Remove some unnecessary headers from driver (e.g. syslog.h)
* Include <poll.h> instead of <sys/poll.h>
* Spelling fixes.

shared/sockets.h

@@ -5,8 +5,6 @@
 #ifndef SOCKETS_H
 #define SOCKETS_H
 
-#include <stdlib.h>
-
 #ifdef HAVE_CONFIG_H
 # include "config.h"
 #endif