Doesn't compile on 32bit

[ohdearaugustin]

This function created a compile error when trying to build with arm32 (CGO_ENABLED=0 GOOS=linux GOARCH=arm go build test.go)

xsync/util.go

Lines 18 to 24 in d5f0f9d

	// murmurhash3 64-bit finalizer
	func hash64(x uintptr) uint64 {
	x = ((x >> 33) ^ x) * 0xff51afd7ed558ccd
	x = ((x >> 33) ^ x) * 0xc4ceb9fe1a85ec53
	x = (x >> 33) ^ x
	return uint64(x)
	}

Following error is shown:

#0 7.331 /go/pkg/mod/github.com/puzpuzpuz/xsync@v1.2.1/util.go:20:24: 0xff51afd7ed558ccd (untyped int constant 18397679294719823053) overflows uintptr
#0 7.331 /go/pkg/mod/github.com/puzpuzpuz/xsync@v1.2.1/util.go:21:24: 0xc4ceb9fe1a85ec53 (untyped int constant 14181476777654086739) overflows uintptr

This can likely be fixed by casting the argument to uint64 before performing the operations.

[puzpuzpuz]

Yes, the readme mentions that only 64-bit builds are currently supported. I may address this when working on an upcoming Map update. In the meantime, if you'd like to contribute a patch, that would be nice.