Change the representation of compiled procedures and other entries:

Change the representation of compiled procedures and other entries:
They are now just the address of an instruction with a gc offset
preceding the instruction and an arity/type word preceding that.
Compiled closures are done by creating a tiny fake compiled code block
which jumps to the right place and sets up the free variables for
reference.

Uuo style links are now just jump instructions to the correct address.
All relocators have been updated to reflect this change.

Variable caches have no type code. The relocators know about this.

Incorporate JRM's fix to signal to close interrupt gap in hp-ux.

New types:
TC_COMPILED_ENTRY
TC_MANIFEST_CLOSURE
TC_LINKAGE_SECTION