mpi: New internal function _gcry_mpi_cmpabs.
* mpi/mpi-cmp.c (_gcry_mpi_cmp): Factor out to ... (do_mpi_cmp): New. Add arg absmode. (_gcry_mpi_cmpabs): New. * src/gcrypt-int.h (mpi_cmpabs): New macro.
(cherry picked from commit 6606ae44e0de1069b29dd4215ee9748280940e1b)
(cherry picked from commit 54620a27f4503e703e219e6e11c4be14ce4e3d35)
- Signed-off-by: Werner Koch <wk@gnupg.org>