Fixed http://bugs.gentoo.org/707772 - fails to build with -fno-common or gcc-10. 
Signed-off-by: Tom Mloduchowski <q@qdot.me>
--- gnugo-3.9.1/engine/globals.c   
+++ gnugo-3.9.1/engine/globals.c  
@@ -136,6 +136,9 @@
                                 * move generation is enabled.
                                 */
 
+int meaningless_white_moves[BOARDMAX];
+int meaningless_black_moves[BOARDMAX];
+
 float best_move_values[10];
 int   best_moves[10];
 float white_score;
--- gnugo-3.9.1/engine/liberty.h
+++ gnugo-3.9.1/engine/liberty.h
@@ -859,8 +859,8 @@
 extern struct worm_data worm[BOARDMAX];
 
 /* Unconditionally meaningless moves. */
-int meaningless_black_moves[BOARDMAX];
-int meaningless_white_moves[BOARDMAX];
+extern int meaningless_black_moves[BOARDMAX];
+extern int meaningless_white_moves[BOARDMAX];
 
 /* Surround cache (see surround.c) */