Cleanup #includes of (mostly a long time) unused header files.

No functional changes.

src/lib/global/constants.c

@@ -36,7 +36,6 @@
 
 #include "gamesdef.h"
 #include "misc.h"
-#include "xy.h"
 
 char *privname = PRVNAM;	/* name of priv user */
 char *privlog = PRVLOG;	/* logname of priv user */

src/lib/global/dir.c

@@ -32,7 +32,6 @@
  */
 
 #include "misc.h"
-#include "xy.h"
 
 /* must agree with DIR_ defines */
 s_char dirch[] = {

src/lib/global/file.c

@@ -48,7 +48,6 @@
 #include "news.h"
 #include "nat.h"
 #include "lost.h"
-#include "optlist.h"
 
 #include "gamesdef.h"
 #include "commodity.h"

src/lib/global/init.c

@@ -36,7 +36,6 @@
 #include "ship.h"
 #include "plane.h"
 #include "product.h"
-#include "nat.h"
 #include "optlist.h"
 #include "global.h"