for-each-ref: Fix quoting style constants.

for-each-ref: Fix quoting style constants.

for-each-ref can accept only one quoting style. For this reason it uses
OPT_BIT for the quoting style switches so that it is easy to check for
more than one bit being set. However, not all symbolic constants were
actually single bit values. In particular:

    $ git for-each-ref --python
    error: more than one quoting style ?

This fixes it.

While we are here, let's also remove the space before the question mark.

Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>