Makefile: set LC_{COLLATE, NUMERIC}=C, unexport LC_ALL

to have reproducible builds (no locale dependencies).

The inspiration came from Linux kernel, commits:
* c051346b7db2 ("Makefile: set LC_CTYPE, LC_COLLATE, LC_NUMERIC to C")
* 07105202bdeb ("Makefile: do not override LC_CTYPE")

NOTE: we don't care about messages not being localized.

Reviewed-by: Richard Palethorpe <rpalethorpe@suse.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Signed-off-by: Petr Vorel <pvorel@suse.cz>
diff --git a/Makefile b/Makefile
index eb12b9d..cb80622 100644
--- a/Makefile
+++ b/Makefile
@@ -1,8 +1,14 @@
 # SPDX-License-Identifier: GPL-2.0-or-later
-# Copyright (c) Linux Test Project, 2009-2021
+# Copyright (c) Linux Test Project, 2009-2022
 # Copyright (c) Cisco Systems Inc., 2009-2010
 # Ngie Cooper, July 2009
 
+# Avoid funny character set dependencies
+unexport LC_ALL
+LC_COLLATE=C
+LC_NUMERIC=C
+export LC_COLLATE LC_NUMERIC
+
 top_srcdir		?= $(CURDIR)
 
 include $(top_srcdir)/include/mk/env_pre.mk