* build-aux/getswdb.sh: Add option --find-sha256sum.
* build-aux/speedo.mk (libgpg_error_sha2): New var. Also for all
other packages.
(SHA2SUM): New.
(SETVARS, SETVARS_W64): Prefer sha256sum over sha1sum.
(installer-from-source): Create swdb fragment.
Signed-off-by: Werner Koch <wk@gnupg.org>