GOOPS: Statically allocate the SMOB class array.

GOOPS: Statically allocate the SMOB class array.

* libguile/goops.c (scm_smob_class): Statically allocate it.
  (create_smob_classes): Don't malloc(3) `scm_smob_class'.

* libguile/goops.h (scm_smob_class): Update declaration.

* libguile/smob.c (scm_make_smob_type, scm_set_smob_apply): When
  checking whether GOOPS is initialized, check whether the first element
  of SCM_SMOB_CLASS is non-zero.