Fix BenchmarkChacha20Poly1305: arg nonceSize shadowed package var

[dagood]

The nonceSize arg shadows package const nonceSize = 12, causing the switch to always hit the first case. This raises a panic (rather than skipping) because the nonce is the wrong size.

const (
	nonceSize  = 12
	nonceSizeX = 24
)
...
func benchmarkChaCha20Poly1305Seal(b *testing.B, buf []byte, nonceSize int) {
...
	var nonce = make([]byte, nonceSize)
...
	switch len(nonce) {
	case nonceSize:
		aead, _ = cng.NewChaCha20Poly1305(key[:])
	case nonceSizeX:
		b.Skip("SizeX not supported")
	}

[Copilot]

Pull request overview

This PR fixes a critical variable shadowing bug in two ChaCha20-Poly1305 benchmark functions where the parameter name nonceSize shadowed the package-level constant nonceSize = 12. This caused the switch statement logic to always match the first case, leading to panics when benchmarks were run with nonce size 24 (the X variant) because the wrong AEAD constructor was used.

Changes:

• Renamed the nonceSize parameter to testNonceSize in benchmarkChaCha20Poly1305Seal and benchmarkChaCha20Poly1305Open functions
• Updated all usages of the parameter within these functions to use the new name

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[qmuntal]

Thanks!