gcc-4.5 signal a possible buffer overflow.
This is a patch that should fix it. Hope it helps.
Regards

--- gnushogi/commondsp.c.old    2010-10-27 11:16:24.000000000 +0200
+++ gnushogi/commondsp.c        2010-10-27 11:17:55.000000000 +0200
@@ -1737,7 +1737,7 @@
                 s[0] = sx[0] = '\0';

                 while(!sx[0])
-                    (void)fgets(sx, 256, stdin);
+                    (void)fgets(sx, 80, stdin);
             }
             else
             {