runtime: fix runtime·raise for dragonfly amd64

Fixes #11847.

Change-Id: I21736a4c6f6fb2f61aec1396ce2c965e3e329e92
Reviewed-on: https://go-review.googlesource.com/12621
Reviewed-by: Mikio Hara <[email protected]>

Author: ianlancetaylor

src/runtime/sys_dragonfly_amd64.s

@@ -125,8 +125,8 @@ TEXT runtime·raise(SB),NOSPLIT,$16
 	MOVL	$496, AX	// lwp_gettid
 	SYSCALL
 	MOVQ	$-1, DI		// arg 1 - pid
-	MOVQ	8(SP), DI	// arg 2 - tid
-	MOVL	sig+0(FP), SI	// arg 3 - signum
+	MOVQ	AX, SI		// arg 2 - tid
+	MOVL	sig+0(FP), DX	// arg 3 - signum
 	MOVL	$497, AX	// lwp_kill
 	SYSCALL
 	RET