ec/asm/ecp_nistz256-x86_64.pl: update commentary with before-after performance data.

# Further optimization by <appro@openssl.org>:

#

#		this/original

# Opteron	+12-49%

# Bulldozer	+14-45%

# P4		+18-46%

# Westmere	+12-34%

# Sandy Bridge	+9-35%

# Ivy Bridge	+9-35%

# Haswell	+8-37%

# Broadwell	+18-58%

# Atom		+15-50%

# VIA Nano	+43-160%

#		this/original	with/without -DECP_NISTZ256_ASM(*)

# Opteron	+12-49%		+110-150%

# Bulldozer	+14-45%		+175-210%

# P4		+18-46%		n/a :-(

# Westmere	+12-34%		+80-87%

# Sandy Bridge	+9-35%		+110-120%

# Ivy Bridge	+9-35%		+110-125%

# Haswell	+8-37%		+140-160%

# Broadwell	+18-58%		+145-210%

# Atom		+15-50%		+130-180%

# VIA Nano	+43-160%	+300-480%

#

# (*)	"without -DECP_NISTZ256_ASM" refers to build with

#	"enable-ec_nistp_64_gcc_128";

#

# Ranges denote minimum and maximum improvement coefficients depending

# on benchmark.

# on benchmark. Lower coefficients are for ECDSA sign, relatively fastest

# server-side operation. Keep in mind that +100% means 2x improvement.

$flavour = shift;

$output  = shift;