patch 8.1.1637: after running tests and clean the XfakeHOME directory remains

Problem:    After running tests and clean the XfakeHOME directory remains.
Solution:   Use "rm -rf". (Hirohito Higashi)
diff --git a/src/version.c b/src/version.c
index 2c370da..b5aac1a 100644
--- a/src/version.c
+++ b/src/version.c
@@ -778,6 +778,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1637,
+/**/
     1636,
 /**/
     1635,