t/lib-httpd: pass LSAN_OPTIONS through apache

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>