games/3dc: Fix crash on boot

The call to XtVaGetValues returns a value that overwrites the `bc` variable and
smashes the stack. Use a long instead.

PR:	255765
Reported by:	grahamperrin@gmail.com
Tested by:	rhurling@
MFH:		2021Q2

(cherry picked from commit 339d443d7b)

games/3dc/Makefile

@@ -2,7 +2,7 @@
 
 PORTNAME=	3dc
 PORTVERSION=	0.8.1
-PORTREVISION=	3
+PORTREVISION=	4
 CATEGORIES=	games
 MASTER_SITES=	SUNSITE/games/strategy
 DISTNAME=	3Dc-${PORTVERSION}

games/3dc/files/patch-xif.c

@@ -0,0 +1,11 @@
+--- xif.c.orig	2021-05-12 08:22:05 UTC
++++ xif.c
+@@ -171,7 +171,7 @@ InitMainWindow( GfxInfo *gfx )
+       /* undo, */ resign,
+       musterTitle
+       /* muster */;
+-  int bg;
++  long bg;
+ 
+   form = XtVaCreateManagedWidget("form", formWidgetClass, gfx->mainWindow,
+                                  NULL);