runtime: optimize aeshashbody with PCALIGN in amd64

For #63678

goos: linux
goarch: amd64
pkg: runtime
cpu: AMD EPYC Processor
                       │  base.txt   │               16.txt                │
                       │   sec/op    │   sec/op     vs base                │
Hash5-2                  4.969n ± 1%   4.583n ± 1%  -7.75% (n=100)
Hash16-2                 4.966n ± 1%   4.536n ± 1%  -8.65% (n=100)
Hash64-2                 5.687n ± 1%   5.726n ± 1%       ~ (p=0.181 n=100)
Hash1024-2               26.73n ± 1%   25.72n ± 1%  -3.76% (n=100)
Hash65536-2              1.345µ ± 0%   1.331µ ± 0%  -1.04% (p=0.000 n=100)
HashStringSpeed-2        12.76n ± 1%   12.53n ± 1%  -1.76% (p=0.000 n=100)
HashBytesSpeed-2         20.13n ± 1%   19.96n ± 1%       ~ (p=0.176 n=100)
HashInt32Speed-2         9.065n ± 1%   9.007n ± 1%       ~ (p=0.247 n=100)
HashInt64Speed-2         9.076n ± 1%   9.027n ± 1%       ~ (p=0.179 n=100)
HashStringArraySpeed-2   33.33n ± 1%   32.94n ± 3%  -1.19% (p=0.028 n=100)
FastrandHashiter-2       16.47n ± 0%   16.54n ± 1%  +0.39% (p=0.013 n=100)
geomean                  17.85n        17.43n       -2.33%

            │   base.txt   │                16.txt                 │
            │     B/s      │      B/s       vs base                │
Hash5-2       959.7Mi ± 1%   1040.4Mi ± 1%  +8.41% (p=0.000 n=100)
Hash16-2      3.001Gi ± 1%    3.285Gi ± 1%  +9.48% (p=0.000 n=100)
Hash64-2      10.48Gi ± 1%    10.41Gi ± 1%       ~ (p=0.179 n=100)
Hash1024-2    35.68Gi ± 1%    37.08Gi ± 1%  +3.92% (p=0.000 n=100)
Hash65536-2   45.41Gi ± 0%    45.86Gi ± 0%  +1.01% (p=0.000 n=100)
geomean       8.626Gi         9.001Gi       +4.35%

Change-Id: Icf98dc935181ea5d30f7cbd5dcf284ec7aef8e9a
Reviewed-on: https://go-review.googlesource.com/c/go/+/539976
Run-TryBot: qiulaidongfeng <[email protected]>
Reviewed-by: Keith Randall <[email protected]>
Auto-Submit: Keith Randall <[email protected]>
Reviewed-by: Keith Randall <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: David Chase <[email protected]>

src/runtime/asm_amd64.s

@@ -1486,6 +1486,7 @@ aes129plus:
 	DECQ	CX
 	SHRQ	$7, CX
 
+	PCALIGN $16
 aesloop:
 	// scramble state
 	AESENC	X8, X8