patch 9.0.0176: checking character options is duplicated and incomplete

Problem:    Checking character options is duplicated and incomplete.
Solution:   Move checking to check_chars_options(). (closes #10863)
diff --git a/src/testdir/test_options.vim b/src/testdir/test_options.vim
index 01418bd..ba08dd7 100644
--- a/src/testdir/test_options.vim
+++ b/src/testdir/test_options.vim
@@ -466,9 +466,17 @@
   call assert_fails('set sessionoptions=curdir,sesdir', 'E474:')
   call assert_fails('set foldmarker={{{,', 'E474:')
   call assert_fails('set sessionoptions=sesdir,curdir', 'E474:')
-  call assert_fails('set listchars=trail:· ambiwidth=double', 'E834:')
+  setlocal listchars=trail:·
+  call assert_fails('set ambiwidth=double', 'E834:')
+  setlocal listchars=trail:-
+  setglobal listchars=trail:·
+  call assert_fails('set ambiwidth=double', 'E834:')
   set listchars&
-  call assert_fails('set fillchars=stl:· ambiwidth=double', 'E835:')
+  setlocal fillchars=stl:·
+  call assert_fails('set ambiwidth=double', 'E835:')
+  setlocal fillchars=stl:-
+  setglobal fillchars=stl:·
+  call assert_fails('set ambiwidth=double', 'E835:')
   set fillchars&
   call assert_fails('set fileencoding=latin1,utf-8', 'E474:')
   set nomodifiable