cmd/asm: correct, complete newly added AVX instructions

Use the standard names, for discoverability.
Use the standard register arguments, for correctness.
Implement all possible arguments, for completeness.
Enable the corresponding tests now that everything is standard.
Update the uses in package runtime.

Fixes #14068.

Change-Id: I8e1af9a41e7d02d98c2a82af3d4cdb3e9204824f
Reviewed-on: https://go-review.googlesource.com/18852
Run-TryBot: Russ Cox <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Rob Pike <[email protected]>

Author: rsc

src/cmd/asm/internal/asm/testdata/amd64enc.s

@@ -551,6 +551,7 @@ const (
 	AFXRSTOR64
 	AFXSAVE
 	AFXSAVE64
+	ALDDQU
 	ALDMXCSR
 	AMASKMOVOU
 	AMASKMOVQ
@@ -751,9 +752,9 @@ const (
 	APCLMULQDQ
 
 	AVZEROUPPER
-	AMOVHDU
-	AMOVNTHD
-	AMOVHDA
+	AVMOVDQU
+	AVMOVNTDQ
+	AVMOVDQA
 	AVPCMPEQB
 	AVPXOR
 	AVPMOVMSKB

src/cmd/internal/obj/x86/a.out.go

@@ -500,6 +500,7 @@ var Anames = []string{
 	"FXRSTOR64",
 	"FXSAVE",
 	"FXSAVE64",
+	"LDDQU",
 	"LDMXCSR",
 	"MASKMOVOU",
 	"MASKMOVQ",
@@ -692,9 +693,9 @@ var Anames = []string{
 	"PSHUFD",
 	"PCLMULQDQ",
 	"VZEROUPPER",
-	"MOVHDU",
-	"MOVNTHD",
-	"MOVHDA",
+	"VMOVDQU",
+	"VMOVNTDQ",
+	"VMOVDQA",
 	"VPCMPEQB",
 	"VPXOR",
 	"VPMOVMSKB",