Fix of snprintf bug in upstream's 20081027 diff.

Signed-off-by: Robin H. Johnson <robbat2@gentoo.org>

diff -Nuar --exclude '*.orig' --exclude '*~' fdutils-5.5-20060227.orig/src/superformat.c fdutils-5.5-20060227/src/superformat.c
--- fdutils-5.5-20060227.orig/src/superformat.c	2019-03-17 14:46:44.051851597 -0700
+++ fdutils-5.5-20060227/src/superformat.c	2019-03-17 14:48:34.550873108 -0700
@@ -1140,7 +1140,7 @@
 		if (verbosity >= 5)
 			printf("calling mformat\n");
 		if (use_2m)
-			snprintf(twom_buffer, 5, "-2 %2d", fd0.dsect);
+			snprintf(twom_buffer, 6, "-2 %2d", fd0.dsect);
 		else
 			twom_buffer[0]='\0';
 		snprintf(command_buffer, 79,