patch 8.2.1552: warnings from asan with clang-11

Problem:    Warnings from asan with clang-11. (James McCoy)
Solution:   Avoid using a NULL pointer. (issue #6811)
diff --git a/src/version.c b/src/version.c
index 901f540..b709939 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1552,
+/**/
     1551,
 /**/
     1550,