make_ext4fs: explicitly call setlocale() before creating image

make_ext4fs: explicitly call setlocale() before creating image

The alphasort(3) function, which is used as comparison function for
scandir(3) is locale dependent (at least in glibc, in which it defers to
strcoll(3)). This patch explicitly calls setlocale(3), setting the
locale to "C".

Currently, there are no other calls to setlocale(), so this does not
change the behaviour. However, we'd like to be sure that in the future
no-one will break that.

Signed-off-by: Wojtek Porczyk <woju@invisiblethingslab.com>