update: Use a scratch sctstr for unit repair simulation

If player->simulation, shiprepair(), planerepair(), landrepair() must
use the bp map, and must not change game state.

Copy the sector to a scratch buffer, update it from the bp map, work
on the sector normally, then write back to the bp map.  This is
simpler and safer.

Since get_materials() loses its connection to the bp map, move its
declaration out of budg.h.

While there, drop an ancient debugging logerror() from landrepair().

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

include/prototypes.h

@@ -672,7 +672,7 @@ extern int prod_land(int, int, struct bp *, int);
 /* main.c */
 /* in server.h */
 /* material.c */
-/* in budg.h */
+extern int get_materials(struct sctstr *, short[], int);
 /* mobility.c */
 extern void mob_sect(void);
 extern void mob_ship(void);