Fix missing setlocale with php 8

When php version = 8, basename('§') does not bug even if LC_ALL is non-UTF-8 locale.
This cause OC_Util::isSetLocaleWorking() to skip setlocale("C.UTF-8").

Fix it by using escapeshellcmd instead of basename.

Signed-off-by: Naoto Kobayashi <naoto.kobayashi4c@gmail.com>