builtin/remote.c: add and use SHOW_INFO_INIT

builtin/remote.c: add and use SHOW_INFO_INIT

In the preceding commit we introduced REF_STATES_INIT, but did not
change the "struct show_info" to have a corresponding
initializer. Let's do that, and make it use "REF_STATES_INIT" and
"STRING_LIST_INIT_DUP", doing that requires changing "list" and
"states" away from being pointers.

The resulting end-state is simpler since we omit the local "info_list"
and "states" variables in show() as well as the memset().

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>