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.

server/drivers/hd44780-serial.h

@@ -6,9 +6,6 @@
 #ifndef HD44780_SERIAL_H
 #define HD44780_SERIAL_H
 
-#include "lcd.h"
-#include "hd44780-low.h"
-
 #define SERIALIF_NAME_LENGTH 20
 #define DEFAULT_DEVICE       "/dev/lcd"