1.0.39.7: Make TRACE :ENCAPSULATE NIL work on PPC.

1.0.39.7: Make TRACE :ENCAPSULATE NIL work on PPC.

  * SIGNAL-CONTEXT-FRAME (debug-int.lisp) was passing a bogus
parameter to COMPUTE-CALLING-FRAME on non-x86oids, causing an
unknown immediate object to be constructed.  Fixed, and KLUDGEd
to still work on x86oids.

  * fun_end_breakpoint_guts (ppc-assem.S) wasn't implemented at
all, just stubbed out to provide the symbols that the core looks
for when compiling MAKE-BOGUS-LRA (debug-int.lisp).

  * The implementation of fun_end_breakpoint_guts on non-PPC is
sparsely explained at best.  Addressed in the new PPC version.

  * The usual implementation of fun_end_breakpoint_guts leaves
setting the LRA header data to MAKE-BOGUS-LRA but this is done
after attempting to create the LRA object, which fails on GENCGC
systems due to the sanity checking of the pointer.  On PPC, this
is addressed by setting the LRA header data by dead reckoning in
ppc-assem.S.

  * In MAKE-BOGUS-LRA, don't bother setting the LRA header data
if it is known to already be correct.