patch 8.1.0509: checking cwd not accessible fails for root

Problem:    Checking cwd not accessible fails for root. (James McCoy)
Solution:   Skip this part of the test for root. (closes #3595)
diff --git a/src/version.c b/src/version.c
index 1e66b3e..fb8a16d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -793,6 +793,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    509,
+/**/
     508,
 /**/
     507,