1.0.38.2: Gencgc error-checking fixes.

1.0.38.2: Gencgc error-checking fixes.

  * Use %p instead of %x in error messages to avoid truncating pointers
to 32 bits on 64 bit platforms.

  * Count pointers to thread stack spaces as being valid (presuming that
they are created by dynamic-extent allocation).

  * Count pointers to funcallable_instance_tramp as being valid (not an
issue on x86oids, but it's a boxed pointer on non-x86oid platforms).