patch 9.0.0251: test output shows up in git

Problem:    Test output shows up in git.
Solution:   Ignore the "failed" directory. (Yao-Ching Huang, closes #10969)
diff --git a/src/version.c b/src/version.c
index a6563d1..1d1de74 100644
--- a/src/version.c
+++ b/src/version.c
@@ -732,6 +732,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    251,
+/**/
     250,
 /**/
     249,