patch 8.1.0546: modeline test with keymap fails

Problem:    Modeline test with keymap fails.
Solution:   Check that the keymap feature is available.

src/testdir/test_modeline.vim

@@ -44,6 +44,9 @@ func Test_modeline_syntax()
 endfunc
 
 func Test_modeline_keymap()
+  if !has('keymap')
+    return
+  endif
   call writefile(['vim: set keymap=greek :', 'nothing'], 'Xmodeline_keymap')
   let modeline = &modeline
   set modeline

src/version.c

@@ -792,6 +792,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    546,
 /**/
     545,
 /**/