* src/context.h (struct gpgme_context): Add proc_all_sigs.
* src/gpgme.c (gpgme_set_ctx_flag): Add flag "proc-all-sigs".
(gpgme_get_ctx_flag): Ditto.
* src/engine-gpg.c (engine.gpg): Add flags.proc_all_sigs.
(have_option_proc_all_sigs): New.
(gpg_set_engine_flags): Set flag from context.
(build_argv): Add --proc-all-sigs if requested and supported.