detect-compiler: make detection independent of locale

`detect-compiler` has accumulated a few compiler dependent workarounds
lately for the more and more ubiquitious gcc12. This is intended to make
CI set-ups work across tool-chain updates, but also help those
developers who build with `DEVELOPER=1`.

Alas, `detect-compiler` uses the locale dependent output of `$(CC) -v`
to parse for the version string, which fails unless it literally
contains ` version`.

Use `LANG=C $(CC) -v` instead to grep for stable output.

Signed-off-by: Michael J Gruber <git@grubix.eu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

detect-compiler

@@ -9,7 +9,7 @@ CC="$*"
 #
 # FreeBSD clang version 3.4.1 (tags/RELEASE...)
 get_version_line() {
-	$CC -v 2>&1 | grep ' version '
+	LANG=C LC_ALL=C $CC -v 2>&1 | grep ' version '
 }
 
 get_family() {