All of the #defines for the TRANSPORT_* flags are hardcoded to be
powers of two. This can be error prone when adding a new flag and
is difficult to read. Update these defines to instead use a shift
operation to generate the flags and reformat them.
Signed-off-by: Brandon Williams <bmwill@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>