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.

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    571,
 /**/
     570,
 /**/