* src/gpgme.c (gpgme_set_ctx_flag): Set flag.
(gpgme_get_ctx_flag): Get flag.
* src/context.h (struct gpgme_context): Add field no_symkey_cache.
* src/engine-gpg.c (struct engine_gpg): Ditto.
(gpg_set_engine_flags): Set flag.
(build_argv): Pass option --no-symkey-cache to gpg.
* tests/run-decrypt.c (print_result): Fix segv for symmetric messages.
(main): New option --no-symkey-cache.
* tests/run-encrypt.c (main): New option --no-symkey-cache.