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.

clients/lcdvc/lcd_link.c

@@ -19,6 +19,7 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <errno.h>
+#include <stdlib.h>
 
 #include "lcd_link.h"
 #include "vc_link.h"