ARMv8 assembly pack: add Cortex performance numbers.

#

#		PMULL[2]	32-bit NEON(*)

# Apple A7	1.76		5.62

# Cortex-A5x	n/a		n/a

# Cortex-A53	1.45		8.39

# Cortex-A57	2.22		7.61

#

# (*)	presented for reference/comparison purposes;

#

#		hardware-assisted	software(*)

# Apple A7	2.31			4.13 (+14%)

# Cortex-A5x	n/a			n/a

# Cortex-A53	2.19			8.73 (+108%)

# Cortex-A57	2.35			7.88 (+74%)

#

# (*)	Software results are presented mostly for reference purposes.

#

#		SHA256-hw	SHA256(*)	SHA512

# Apple A7	1.97		10.5 (+33%)	6.73 (-1%(**))

# Cortex-A5x	n/a		n/a		n/a

# Cortex-A53	2.38		15.6 (+110%)	10.1 (+190%(***))

# Cortex-A57	2.31		11.6 (+86%)	7.51 (+260%(***))

# 

# (*)	Software SHA256 results are of lesser relevance, presented

#	mostly for informational purposes.

# (**)	The result is a trade-off: it's possible to improve it by

#	10%, but at the cost of 20% loss on Cortex-A5x.

#	10% (or by 1 cycle per round), but at the cost of 20% loss

#	on Cortex-A53 (or by 4 cycles per round).

# (***)	Super-impressive coefficients over gcc-generated code are

#	indication of some compiler "pathology", most notably code

#	generated with -mgeneral-regs-only is significanty faster

#	and lags behind assembly only by 50-90%.

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