This gives git servers a chance to display remote error messages in
the user's preferred language.
Limit the number of languages to 1,000 because q-value must not be
smaller than 0.001, and limit the length of Accept-Language header to
4,000 bytes for some HTTP servers which cannot accept such long header.
Signed-off-by: Yi EungJun <eungjun.yi@navercorp.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>