* gas/sparc/synth64.s: Add checks for single register signx/clruw.
* gas/sparc/set64.s: Add tests for setuw and setsw synthetic insns.
* gas/sparc/prefetch.d: Add -64 as switch.
* gas/sparc/rdpr.d: Ditto.
* gas/sparc/wrpr.d: Ditto.
* gas/sparc/synth64.d: Ditto, reflect synth64.s changes.
* gas/sparc/reloc64.d: Add -64 as switch, be more tolerant, as
current gas outputs %hi(0) and not %hi(0x0).
* gas/sparc/set64.d: Add -64 as switch, reflect set64.s changes and
optimizations for setx instruction.
* gas/sparc/sparc.exp: Do sparc64*-*-* checks if it is any of the
compiled-in targets.