patch 8.0.0531: test with long directory name fails on non-unix systems

Problem:    Test with long directory name fails on non-unix systems.
Solution:   Skip the test on non-unix systems.

src/testdir/test_edit.vim

@@ -1324,6 +1324,10 @@ func! Test_edit_rightleft()
 endfunc
 
 func Test_edit_complete_very_long_name()
+  if !has('unix')
+    " Long directory names only work on Unix.
+    return
+  endif
   let save_columns = &columns
   set columns=5000
   call assert_equal(5000, &columns)

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    531,
 /**/
     530,
 /**/