test: drive Korean and Vietnamese through the engine's own transstr

ko_test and vi_test replayed keys with private copies of transstr's
loop, and test_util reimplemented the shown preedit; the engine exports
impre(Im*, Str*) and transstr() instead, so a change to composition
rules is one edit.

tests/test_util.c

@@ -20,23 +20,3 @@ checkstr(struct ct *t, char *where, char *want, Str *got)
 	return CT_ERRORF(t, "%s: want \"%s\", got \"%s\"",
 		where, want, buf);
 }
-
-Str
-shownpre(Im *state)
-{
-	Str mapped, shown;
-
-	if(state->l->lang == LangJP || state->l->lang == LangJPK){
-		shown = state->pre;
-		if(state->raw.n == 0)
-			return shown;
-		if(mapget(state->l->map, &state->raw, &mapped))
-			sappend(&shown, &mapped);
-		else
-			sappend(&shown, &state->raw);
-		return shown;
-	}
-	if(state->l->map != nil && mapget(state->l->map, &state->pre, &shown))
-		return shown;
-	return state->pre;
-}