patch 9.0.0166: when using text properties line text length computed twice

Problem:    When using text properties the line text length is computed twice.
Solution:   If the text lenght was already computed don't do it again.
diff --git a/src/version.c b/src/version.c
index bccf787..7544d6f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -736,6 +736,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    166,
+/**/
     165,
 /**/
     164,