patch 8.0.0266: compiler warning for using uninitialized variable

Problem:    Compiler warning for using uninitialized variable.
Solution:   Set tab_number also when there is an error.
diff --git a/src/version.c b/src/version.c
index bf28557..ba1501c 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    266,
+/**/
     265,
 /**/
     264,