Makefile: set LC_CTYPE, LC_COLLATE, LC_NUMERIC to C

There are a number of common Unix constructs like character ranges in
grep/sed/awk which don't work as expected with LC_COLLATE set to other
than C.  Similarly, set LC_CTYPE and LC_NUMERIC to C to avoid other
nasty surprises.

In order to make sure these actually take effect we also have to
clear LC_ALL.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Acked-by: Michal Marek <mmarek@sues.cz>
Acked-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Roland Dreier <rdreier@cisco.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
LKML-Reference: <4B2A1761.4070904@suse.cz>