patch 8.0.1679: compiler warning for printf format

Problem:    Compiler warning for printf format. (Chdiza)
Solution:   Change type to "long long". (closes #2791)
diff --git a/src/ops.c b/src/ops.c
index 8b895d8..b1c1d36 100644
--- a/src/ops.c
+++ b/src/ops.c
@@ -7555,7 +7555,7 @@
 	bom_count = bomb_size();
 	if (bom_count > 0)
 	    vim_snprintf((char *)IObuff + STRLEN(IObuff), IOSIZE,
-					      _("(+%ld for BOM)"), bom_count);
+				   _("(+%lld for BOM)"), (long long)bom_count);
 #endif
 	if (dict == NULL)
 	{