send-pack: clean up extra_have oid array

send-pack: clean up extra_have oid array

Commit c8009635785e ("fetch-pack, send-pack: clean up shallow oid
array", 2024-09-25) cleaned up the shallow oid array in cmd_send_pack,
but didn't clean up extra_have, which is still leaked at program exit.
I suspect the particular tests in t5539 don't trigger any additions to
the extra_have array, which explains why the tests can pass leak free
despite this gap.

Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>