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>