core: Simplify calling convention of mkheader.
* src/Makefile.am (gpg-error.h): Remove HOST_OS from mkheader call. * src/mkheader.c (canon_host_triplet): Add return arg r_os. (main): Remove first arg and derive host_os from host_triplet.
No need to let the caller pass the host_os, we can derive it from the
triplet.
- Signed-off-by: Werner Koch <wk@gnupg.org>