GOOPS: Statically allocate the PORT class array.

GOOPS: Statically allocate the PORT class array.

* libguile/goops.c (scm_port_class): Statically allocate it.
  (create_port_classes): Don't use `scm_calloc ()'.

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

* libguile/ports.c (scm_make_port_type): When checking whether
  GOOPS is initialized, check whether the first element of
  SCM_PORT_CLASS is non-zero.