vim-patch:8.1.2172: spell highlight is wrong at start of the line

Problem:    Spell highlight is wrong at start of the line.
Solution:   Fix setting the "v" variable. (closes vim/vim#5078)
7751d1d1a3

Skip spell tests in OpenBSD.

Nvim or screen likely crashed.
Revist once issue #12104 is fixed.
Skip the test for the following reasons:
- unknown regression caused by https://github.com/neovim/neovim/issues/12104
- cannot revert failing test from ed0d135247

src/nvim/screen.c

@@ -3476,6 +3476,7 @@ win_line (
          * Only do this when there is no syntax highlighting, the
          * @Spell cluster is not used or the current syntax item
          * contains the @Spell cluster. */
+        v = (long)(ptr - line);
         if (has_spell && v >= word_end && v > cur_checked_col) {
           spell_attr = 0;
           if (!attr_pri) {