patch 8.2.0186: a couple of tests may fail when features are missing

Problem:    A couple of tests may fail when features are missing.
Solution:   Check for features. (Dominique Pelle, closes #5561)

src/testdir/test_functions.vim

@@ -1999,7 +1999,7 @@ func Test_range()
   set tagfunc=
   
   " term_start()
-  if has('terminal')
+  if has('terminal') && has('termguicolors')
     call assert_fails('call term_start(range(3, 4))', 'E474:')
     let g:terminal_ansi_colors = range(16)
     call assert_fails('call term_start("ls", #{term_finish: "close"})', 'E475:')

src/testdir/test_highlight.vim

@@ -622,6 +622,7 @@ endfunc
 
 func Test_wincolor_listchars()
   CheckScreendump
+  CheckFeature conceal
 
   let lines =<< trim END
 	call setline(1, ["one","\t\tsome random text enough long to show 'extends' and 'precedes' includingnbsps, preceding tabs and trailing spaces    ","three"])

src/version.c

@@ -742,6 +742,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    186,
 /**/
     185,
 /**/