patch 8.2.4594: need to write script to a file to be able to source them

Problem:    Need to write script to a file to be able to source them.
Solution:   Make ":source" use lines from the current buffer. (Yegappan
            Lakshmanan et al., closes #9967)

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4594,
 /**/
     4593,
 /**/