kbuild: replace LANG=C with LC_ALL=C

LANG gives a weak default to each LC_* in case it is not explicitly
defined. LC_ALL, if set, overrides all other LC_* variables.

  LANG  <  LC_CTYPE, LC_COLLATE, LC_MONETARY, LC_NUMERIC, ...  <  LC_ALL

This is why documentation such as [1] suggests to set LC_ALL in build
scripts to get the deterministic result.

LANG=C is not strong enough to override LC_* that may be set by end
users.

[1]: https://reproducible-builds.org/docs/locales/

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Reviewed-by: Matthias Maennich <maennich@google.com>
Acked-by: Matthieu Baerts <matthieu.baerts@tessares.net> (mptcp)
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/scripts/tags.sh b/scripts/tags.sh
index fd96734..db8ba41 100755
--- a/scripts/tags.sh
+++ b/scripts/tags.sh
@@ -326,5 +326,5 @@
 
 # Remove structure forward declarations.
 if [ -n "$remove_structs" ]; then
-    LANG=C sed -i -e '/^\([a-zA-Z_][a-zA-Z0-9_]*\)\t.*\t\/\^struct \1;.*\$\/;"\tx$/d' $1
+    LC_ALL=C sed -i -e '/^\([a-zA-Z_][a-zA-Z0-9_]*\)\t.*\t\/\^struct \1;.*\$\/;"\tx$/d' $1
 fi