include: Drop update.h

update.h is a convenience header to include headers commonly needed in
update code.  The price for the convenience is superfluous recompiles.
Include necessary headers directly, and drop update.h

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>

src/lib/update/mobility.c

@@ -34,12 +34,15 @@
 
 #include <config.h>
 
+#include "file.h"
 #include "game.h"
 #include "land.h"
+#include "optlist.h"
 #include "plane.h"
+#include "prototypes.h"
+#include "sect.h"
 #include "server.h"
 #include "ship.h"
-#include "update.h"
 
 static int do_upd_checking;