nsdeps: make generated patches independent of locale

scripts/nsdeps automatically generates a patch to add MODULE_IMPORT_NS
tags, and what is nicer, it sorts the lines alphabetically with the
'sort' command. However, the output from the 'sort' command depends on
locale.

For example, I got this:

$ { echo usbstorage; echo usb_storage; } | LANG=en_US.UTF-8 sort
usbstorage
usb_storage
$ { echo usbstorage; echo usb_storage; } | LANG=C sort
usb_storage
usbstorage

So, this means people might potentially send different patches.

This kind of issue was reported in the past, for example,
commit f55f2328 ("kbuild: make sorting initramfs contents
independent of locale").

Adding 'LANG=C' is a conventional way of fixing when a deterministic
result is desirable.

I added 'LANG=C' very close to the 'sort' command since changing
locale affects the language of error messages etc. We should respect
users' choice as much as possible.

Reviewed-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>