block/vvfat: Unify the mkdir() call

block/vvfat: Unify the mkdir() call

There is a difference in the mkdir() call for win32 and non-win32
platforms, and currently is handled in the codes with #ifdefs.

glib provides a portable g_mkdir() API and we can use it to unify
the codes without #ifdefs.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20221006151927.2079583-6-bmeng.cn@gmail.com>
Message-Id: <20221027183637.2772968-14-alex.bennee@linaro.org>