0.8.21.6:

0.8.21.6:
	Fix some x86-64 issues:
        * DOUBLE-FLOAT-{HIGH,LOW}-BITS on doubles stored on the stack
          had a off-by-one error on x86-64. (Discovered using Paul Dietz'
          random type propagation tester).
        * Fix a thinko in the pointer detection code of MAKE-VALID-LISP-OBJ.
          This was causing creation of invalid lispobjs under some
          rare circumstances, followed by failing GC assertions. (Discovered
          using Paul Dietz' random type propagation tester).
        * The disassembly done by the compiler if *COMPILER-TRACE-OUTPUT*
          is set was erroring out on x86-64 RIP addressing. Add a
          workaround.
        * Add missing case to !DEFINE-BYTE-BASHERS for a bitsize of 64.