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 #5078)

src/drawline.c

@@ -1824,6 +1824,7 @@ 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;
@@ -1874,7 +1875,8 @@ win_line(
 			    // Remember that the good word continues at the
 			    // start of the next line.
 			    checked_lnum = lnum + 1;
-			    checked_col = (int)((p - nextline) + len - nextline_idx);
+			    checked_col = (int)((p - nextline)
+							 + len - nextline_idx);
 			}
 
 			// Turn index into actual attributes.