Instead of just storing the string and then later calling our own
parsing function 'parse_fetch_recurse_submodules_arg', make use of the
function callback 'option_fetch_parse_recurse_submodules' that was
introduced in the last patch. Also move all submodule recursing variables
in one spot at the top of the file.
Signed-off-by: Stefan Beller <sbeller@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>