patch 8.2.4669: in compiled code len('string') is not inlined

Problem:    In compiled code len('string') is not inlined.
Solution:   Compute the length at compile time if possible. (closes #10065)
diff --git a/src/version.c b/src/version.c
index 311b878..92198be 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4669,
+/**/
     4668,
 /**/
     4667,