patch 8.0.0571: negative line number when using :z^ in an empty buffer

Problem:    The cursor line number becomes negative when using :z^ in an empty
            buffer. (neovim #6557)
Solution:   Correct the line number.  Also reset the column.
diff --git a/src/version.c b/src/version.c
index c169765..81b98c1 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    571,
+/**/
     570,
 /**/
     569,