We have a function which parses a buffer with a signature at the end,
parse_signature, and this function is used for signed tags. However,
we'll need to store values for multiple algorithms, and we'll do this by
using a header for the non-default algorithm.
Adjust the parse_signature interface to store the parsed data in two
strbufs and turn the existing function into parse_signed_buffer. The
latter is still used in places where we know we always have a signed
buffer, such as push certs.
Adjust all the callers to deal with this new interface.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>