cmd/internal/obj/x86: remove unused const

Since https://go-review.googlesource.com/24040 we no longer pad functions
in asm6, so funcAlign is unused. Delete it.

Change-Id: Id710e545a76b1797398f2171fe7e0928811fcb31
Reviewed-on: https://go-review.googlesource.com/38134Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/internal/obj/x86/asm6.go

@@ -56,7 +56,6 @@ const (
 	//
 	LoopAlign  = 16
 	MaxLoopPad = 0
-	funcAlign  = 16
 )
 
 type Optab struct {