BUILD: checks: don't include server.h

server.h needs checks.h since it references the struct check, but depending
on the include order it will fail if check.h is included first due to this
one including server.h in turn while it doesn't need it.

include/types/checks.h

@@ -22,7 +22,6 @@
 #include <types/connection.h>
 #include <types/obj_type.h>
 #include <types/task.h>
-#include <types/server.h>
 
 /* enum used by check->result. Must remain in this order, as some code uses
  * result >= CHK_RES_PASSED to declare success.