Description: Avoid defining objects twice
Author: Stephen Kitt <skitt@debian.org>

This allows building with -fno-common (the GCC 10 default).

--- a/texmap/ntmap.c
+++ b/texmap/ntmap.c
@@ -55,7 +55,7 @@
 int     Lighting_on=1;                  // initialize to no lighting
 int	Tmap_flat_flag = 0;		//	1 = render texture maps as flat shaded polygons.
 int	Current_seg_depth;		// HACK INTERFACE: how far away the current segment (& thus texture) is
-int	Max_perspective_depth;
+extern int	Max_perspective_depth;
 int	Max_flat_depth;
 
 // These variables are the interface to assembler.  They get set for each texture map, which is a real waste of time.