cmd/dist: add link/internal/sparc64 to bootstrapDirs
cmd/dist: add link/internal/sparc64 to bootstrapDirs

Change-Id: I9463b7ebb9895e1d094d6f86bf234747165525e7

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