gpgsm: Strip trailing zeroes from detached signatures.
* common/ksba-io-support.c: Include tlv.h (struct reader_cb_parm_s): Add new fields. (starts_with_sequence): New. (simple_reader_cb): Handle stripping. * common/ksba-io-support.h (GNUPG_KSBA_IO_STRIP): New. (gnupg_ksba_create_reader): Handle the new flag. * sm/verify.c (gpgsm_verify): Use the new flag for detached signatures.
Note that this works only if --assume-binary is given. The use case
for the feature is PDF signature checking where the PDF specs require
that the detached signature is padded with zeroes.