xcalloc() takes two arguments: the number of elements and their size.
parse_refspec_internal passes the arguments in reverse order, passing the
size of a refspec, followed by the number to allocate.
Rearrange them so they are in the correct order.
Signed-off-by: Brian Gesiak <modocache@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>