patch 8.1.0552: saved last search pattern may not be restored

Problem:    Saved last search pattern may not be restored.
Solution:   Call restore_last_search_pattern().  Add a check for balancing
            saving and restoring the last search pattern.
diff --git a/src/version.c b/src/version.c
index 29f3ec5..1fc35ed 100644
--- a/src/version.c
+++ b/src/version.c
@@ -793,6 +793,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    552,
+/**/
     551,
 /**/
     550,