patch 8.1.0866: build file dependencies are outdated

Problem:    Build file dependencies are outdated. (John Little)
Solution:   Run "make proto" and "make depend".
diff --git a/src/version.c b/src/version.c
index 1bedce1..14f1894 100644
--- a/src/version.c
+++ b/src/version.c
@@ -784,6 +784,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    866,
+/**/
     865,
 /**/
     864,