patch 8.2.2117: some functions use any value as a string

Problem:    Some functions use any value as a string.
Solution:   Check that the value is a non-empty string.
diff --git a/src/version.c b/src/version.c
index efb17f3..21d051e 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2117,
+/**/
     2116,
 /**/
     2115,