patch 8.2.1884: compiler warning for uninitialized variable

Problem:    Compiler warning for uninitialized variable. (John Marriott)
Solution:   Initialize with NULL.
diff --git a/src/version.c b/src/version.c
index 720dc3a..56bf8f6 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1884,
+/**/
     1883,
 /**/
     1882,