[llvm] [AArch64] Extend performActiveLaneMaskCombine for more than two extracts (PR #146725)

[Paul Walker via llvm-commits]

https://github.com/paulwalker-arm approved this pull request.

There's still David's comment linked to `test_fixed_extract` but otherwise this looks good to me.

https://github.com/llvm/llvm-project/pull/146725