func newCRC64() hash.Hash {
	return crc64Hash{Hash64: crc64.New(crc64Table)}
}
newCRC64 returns a CRC-64 hash that returns the 64-bit value in
little-endian encoding using the ECMA polynomial.
package xz
import (
	"hash"
	"hash/crc32"
	"hash/crc64"
)
type crc32Hash struct {
	hash.Hash32
}
func (h crc32Hash) Sum(b []byte) []byte {
	p := make([]byte, 4)
	putUint32LE(p, h.Hash32.Sum32())
	b = append(b, p...)
	return b
}
func newCRC32() hash.Hash {
	return crc32Hash{Hash32: crc32.NewIEEE()}
}
type crc64Hash struct {
	hash.Hash64
}
func (h crc64Hash) Sum(b []byte) []byte {
	p := make([]byte, 8)
	putUint64LE(p, h.Hash64.Sum64())
	b = append(b, p...)
	return b
}
var crc64Table = crc64.MakeTable(crc64.ECMA)