[3.12] Fix c-analyzer for GCC: ignore LANG env var (GH-106173) (#106178)

Fix c-analyzer for GCC: ignore LANG env var (GH-106173)

The c-analyzer doesn't support GCC localized messages, so just unset
the LANG environment variable.
(cherry picked from commit 1f74b9e933d546a015e8497e3b8728357196acc8)

Co-authored-by: Victor Stinner <vstinner@python.org>