1.0.38.5: PPC character handling fixes.

1.0.38.5: PPC character handling fixes.

  * SAP-REF-32LE referred to SAP-REF-16 instead of SAP-REF-16LE on
non-x86oid platforms, incorrect for all big-endian targets.

  * The immediate-character MOVE function was using a 16-bit-only
load instruction, which was insufficient for unicode operation.

  * The -c (constant) character compare VOPs use a compare
instruction with a 16-bit immediate field.  Disabled on unicode
(there's no good way to conditionally use them when the code
point of the constant character fits a signed-byte 16).

  * Cleaned up some external-format.impure.lisp test-cases, adding
with-test and names as needed.