cmd/link/internal/sparc64: make addpltsym more like the other architectures
cmd/link/internal/sparc64: make addpltsym more like the other architectures

Change-Id: I926c5c148f7c61055f5f08814744d7871d2d5291

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