Allow return_to_compiled_code to return to compiled entries.

Allow return_to_compiled_code to return to compiled entries.

The earlier compiled entry/return split left various utility calls
pushing compiled entries, rather than compiled return addresses, for
continuations on the stack -- notably interrupt routines, the linker
utility, and interpreter calls.

I arranged for these to all to use RETURN_TO_SCHEME_ENTRY (or
JUMP_TO_CC_ENTRY), but missed one spot: the continuations constructed
by STACK-FRAME->CONTINUATION, which use return_to_compiled_code,
which in turn expected a compiled return rather than a compiled entry
and choked.

The interrupt routines, linker utility, and interpreter calls should
all be adapted to take returns rather than entries (which is another
ABI-breaking flag day), but this will do for now.