Fix launch to require petrol for launching satellites

launch_sat() failed to call msl_equip().  Change msl_equip() to take
the mission character as argument, because the old hardcoded 'p' isn't
appropriate for satellites.  Best fit for satellites is 'r' for
reconnaissance, but mission_pln_equip() doesn't accept that
(pln_equip() does).  Fix that as well.

src/lib/subs/mission.c

@@ -1036,6 +1036,7 @@ mission_pln_equip(struct plist *plp, struct ichrstr *ip, int flags,
 		needed = load;
 	    }
 	    break;
+	case 'r':		/* reconnaissance */
 	case 0:			/* plane interception */
 	    break;
 	default: