crypto/cipher: optimize safeXORBytes

[tbeeck]

Optimize safeXORBytes based on this conversation: #35381

Before:

BenchmarkXORBytes/8Bytes-12 202142712 5.947 ns/op 1345.12 MB/s
BenchmarkXORBytes/128Bytes-12 19122530 63.56 ns/op 2013.72 MB/s
BenchmarkXORBytes/2048Bytes-12 1309760 908.1 ns/op 2255.28 MB/s
BenchmarkXORBytes/32768Bytes-12 72750 14673 ns/op 2233.20 MB/s
PASS
ok crypto/cipher 6.437s

After:

BenchmarkXORBytes/8Bytes-12 189982386 5.441 ns/op 1470.39 MB/s
BenchmarkXORBytes/128Bytes-12 42866022 28.41 ns/op 4505.66 MB/s
BenchmarkXORBytes/2048Bytes-12 3013195 406.8 ns/op 5034.92 MB/s
BenchmarkXORBytes/32768Bytes-12 186090 6396 ns/op 5123.55 MB/s
PASS
ok crypto/cipher 5.808

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Message from Daniel Martí:

Patch Set 3: Trust+1

(1 comment)

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Message from Tim Beck:

Patch Set 3:

(1 comment)

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Message from Ingo Oeser:

Patch Set 3:

(2 comments)

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Patch Set 3:

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Patch Set 4:

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Message from Daniel Martí:

Patch Set 4: Trust+1

(1 comment)

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[tbeeck]

Apologies for abandoning some time ago--as this function was removed from the package with the change to export the XOR implementation, I will close this review