* tests/gpgscm/opdefines.h (put, get): Check arguments.  Also rename
to 'set-symbol-property' and 'symbol-property', the names used by
Guile, because put and get are too unspecific.
* tests/gpgscm/scheme.c (hasprop): Only symbols have property lists.
(get_property): New function.
(set_property): Likewise.
(opexe_4): Use the new functions.