vim-patch:8.1.2371: FEAT_TEXT_PROP is a confusing name (#35466)

Problem:    FEAT_TEXT_PROP is a confusing name.
Solution:   Use FEAT_PROP_POPUP. (Naruhiko Nishino, closes vim/vim#5291)

05ad5ff0ab

textprop,popuwin remain N/A features.
getchar.c has the relevant code changes.

Port runtest.vim changes from patch v8.1.1561.

Co-authored-by: Bram Moolenaar <Bram@vim.org>

test/old/testdir/test_execute_func.vim

@@ -99,7 +99,7 @@ func Test_win_execute()
   let line = win_execute(134343, 'echo getline(1)')
   call assert_equal('', line)
 
-  if has('textprop')
+  if has('popupwin')
     let popupwin = popup_create('the popup win', {'line': 2, 'col': 3})
     redraw
     let line = 'echo getline(1)'->win_execute(popupwin)