Remove dead code

After e9931bfb75, the locale argument of SB_lower_char() is never
NULL, so the branch that deals with NULL can be removed (similar to
how e9931bfb75 for example removed those branches in str_tolower()).

Reviewed-by: Jeff Davis <pgsql@j-davis.com>
Discussion: https://www.postgresql.org/message-id/4f562d84-87f4-44dc-8946-01d6c437936f@eisentraut.org

src/backend/utils/adt/like.c

@@ -95,10 +95,8 @@ SB_lower_char(unsigned char c, pg_locale_t locale, bool locale_is_c)
 {
 	if (locale_is_c)
 		return pg_ascii_tolower(c);
-	else if (locale)
-		return tolower_l(c, locale->info.lt);
 	else
-		return pg_tolower(c);
+		return tolower_l(c, locale->info.lt);
 }