t/lib-httpd: pass LSAN_OPTIONS through apache

Just as we instruct Apache to pass through ASAN_OPTIONS (so that server-side Git programs it spawns will respect our options while running the tests), we should do the same with LSAN_OPTIONS. Otherwise trying to collect a list of leaks like: export LSAN_OPTIONS=exitcode=0:log_path=/tmp/lsan make SANITIZE=leak test won't work for http tests (the server-side programs won't log their leaks to the right place, and they'll prematurely die, producing a spurious test failure). Signed-off-by: Jeff King <peff@peff.net> Acked-by: Josh Steadmon <steadmon@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>