fix use of *reflect.SliceHeader

[aidan-kwon]

Proposed changes

go vet warns the current use of *reflect.SliceHeader.
The code is changed in more recommended way.

consensus/gxhash/algorithm.go:146:12: possible misuse of reflect.SliceHeader
consensus/gxhash/algorithm.go:149:37: possible misuse of reflect.SliceHeader
consensus/gxhash/algorithm.go:287:12: possible misuse of reflect.SliceHeader
consensus/gxhash/algorithm.go:290:39: possible misuse of reflect.SliceHeader
consensus/gxhash/gxhash.go:106:12: possible misuse of reflect.SliceHeader
consensus/gxhash/gxhash.go:110:42: possible misuse of reflect.SliceHeader

The rationale of this change: golang/go#40701

All changes in this PR are imported from ethereum/go-ethereum#21372 ethereum/go-ethereum#22696

Types of changes

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• Bugfix
• New feature or enhancement
• Others

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[baerae-colin]

LGTM. those are not used in our production, though. :)