cmd/compile/internal/sparc64: exclude more registers in excluderegs
cmd/compile/internal/sparc64: exclude more registers in excluderegs

The relationship between resvd and excluderegs still eludes me.

Change-Id: Ie85102d6b379de54ca1109def663d4bb0e136803

4ad/go,4ad/go,4ad/go,4ad/go,4ad/go,4ad/go,4ad/go,4ad/go