Restore PPC build.

Adjust register lifetime in calling VOPs.

Thanks to Alastair Bridgewater.
Fix the recent %vector-widetag-and-n-bits change.

Handle extended-char, interval type designators, and union types.
UPGRADED-ARRAY-ELEMENT-TYPE: more thoroughly signal errors on unknown types.

Intersection and union types containing unknown types were handled incorrectly.
(upgraded-array-element-type '(and fixnum unknown)) => was FIXNUM.