x86asm: include size suffix on popcnt instruction

Update golang/go#48584

Change-Id: I2c770aaf88e15f8987dc8f1d974127b02b220777
Reviewed-on: https://go-review.googlesource.com/c/arch/+/351889
Trust: Keith Randall <[email protected]>
Run-TryBot: Keith Randall <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>

Author: randall77

x86/x86asm/plan9x.go

@@ -204,6 +204,7 @@ var plan9Suffix = [maxOp + 1]bool{
 	OUT:       true,
 	POP:       true,
 	POPA:      true,
+	POPCNT:    true,
 	PUSH:      true,
 	PUSHA:     true,
 	RCL:       true,

x86/x86asm/testdata/decode.txt

@@ -6518,10 +6518,10 @@ f30faec8|11223344556677885f5f5f5f	64	gnu	rdgsbase %eax
 f30faec8|11223344556677885f5f5f5f	64	intel	rdgsbase eax
 f30faec8|11223344556677885f5f5f5f	64	plan9	RDGSBASE AX
 f30fb811|223344556677885f5f5f5f5f	32	intel	popcnt edx, dword ptr [ecx]
-f30fb811|223344556677885f5f5f5f5f	32	plan9	POPCNT 0(CX), DX
+f30fb811|223344556677885f5f5f5f5f	32	plan9	POPCNTL 0(CX), DX
 f30fb811|223344556677885f5f5f5f5f	64	gnu	popcnt (%rcx),%edx
 f30fb811|223344556677885f5f5f5f5f	64	intel	popcnt edx, dword ptr [rcx]
-f30fb811|223344556677885f5f5f5f5f	64	plan9	POPCNT 0(CX), DX
+f30fb811|223344556677885f5f5f5f5f	64	plan9	POPCNTL 0(CX), DX
 f30fbc11|223344556677885f5f5f5f5f	32	intel	tzcnt edx, dword ptr [ecx]
 f30fbc11|223344556677885f5f5f5f5f	32	plan9	TZCNT 0(CX), DX
 f30fbc11|223344556677885f5f5f5f5f	64	gnu	tzcnt (%rcx),%edx
@@ -6565,18 +6565,18 @@ f3480faec8|11223344556677885f5f5f	64	intel	rdgsbase rax
 f3480faec8|11223344556677885f5f5f	64	plan9	RDGSBASE AX
 f3480fb811|223344556677885f5f5f5f	64	gnu	popcnt (%rcx),%rdx
 f3480fb811|223344556677885f5f5f5f	64	intel	popcnt rdx, qword ptr [rcx]
-f3480fb811|223344556677885f5f5f5f	64	plan9	POPCNT 0(CX), DX
+f3480fb811|223344556677885f5f5f5f	64	plan9	POPCNTQ 0(CX), DX
 f3480fbc11|223344556677885f5f5f5f	64	gnu	tzcnt (%rcx),%rdx
 f3480fbc11|223344556677885f5f5f5f	64	intel	tzcnt rdx, qword ptr [rcx]
 f3480fbc11|223344556677885f5f5f5f	64	plan9	TZCNT 0(CX), DX
 f3480fbd11|223344556677885f5f5f5f	64	gnu	lzcnt (%rcx),%rdx
 f3480fbd11|223344556677885f5f5f5f	64	intel	lzcnt rdx, qword ptr [rcx]
 f3480fbd11|223344556677885f5f5f5f	64	plan9	LZCNT 0(CX), DX
 f3660fb811|223344556677885f5f5f5f	32	intel	popcnt dx, word ptr [ecx]
-f3660fb811|223344556677885f5f5f5f	32	plan9	POPCNT 0(CX), DX
+f3660fb811|223344556677885f5f5f5f	32	plan9	POPCNTW 0(CX), DX
 f3660fb811|223344556677885f5f5f5f	64	gnu	popcnt (%rcx),%dx
 f3660fb811|223344556677885f5f5f5f	64	intel	popcnt dx, word ptr [rcx]
-f3660fb811|223344556677885f5f5f5f	64	plan9	POPCNT 0(CX), DX
+f3660fb811|223344556677885f5f5f5f	64	plan9	POPCNTW 0(CX), DX
 f3660fbc11|223344556677885f5f5f5f	32	intel	tzcnt dx, word ptr [ecx]
 f3660fbc11|223344556677885f5f5f5f	32	plan9	TZCNT 0(CX), DX
 f3660fbc11|223344556677885f5f5f5f	64	gnu	tzcnt (%rcx),%dx