* tests/gpgscm/scheme-private.h (struct scheme): Add field 'flags'.
* tests/gpgscm/scheme.c (S_OP_MASK): New macro.
(S_FLAG_MASK, s_set_flag, s_clear_flag, s_get_flag): Likewise.
(_s_return): Unpack the encoded opcode and flags.
(s_save): Encode the flags along with the opcode.  Use normal
integers to encode the result.
(scheme_init_custom_alloc): Initialize 'op' and 'flags'.