patch 8.0.1509: test for failing drag-n-drop command no longer fails

Problem:    Test for failing drag-n-drop command no longer fails.
Solution:   Check for the "dnd" feature.

src/testdir/test_normal.vim

@@ -2176,7 +2176,11 @@ func! Test_normal44_textobjects2()
 endfunc
 
 func! Test_normal45_drop()
-  " basic test for :drop command
+  if !has('dnd')
+    return
+  endif
+
+  " basic test for drag-n-drop
   " unfortunately, without a gui, we can't really test much here,
   " so simply test that ~p fails (which uses the drop register)
   new

src/version.c

@@ -771,6 +771,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1509,
 /**/
     1508,
 /**/