[dev.ssa] fix equivalence class after aux/auxint refactor.

This caused the following code snippet to be miscompiled

	var f int
	x := g(&f)
	f = 10

Moving the store of 10 above the function call.

Change-Id: Ic6951f5e7781b122cd881df324a38e519d6d66f0
Reviewed-on: https://go-review.googlesource.com/11073
Reviewed-by: Keith Randall <khr@golang.org>

src/cmd/compile/internal/ssa/cse.go

@@ -29,12 +29,13 @@ func cse(f *Func) {
 		op     Op
 		typ    Type
 		aux    interface{}
+		auxint int64
 		nargs  int
 	}
 	m := map[key]eqclass{}
 	for _, b := range f.Blocks {
 		for _, v := range b.Values {
-			k := key{v.Op, v.Type, v.Aux, len(v.Args)}
+			k := key{v.Op, v.Type, v.Aux, v.AuxInt, len(v.Args)}
 			m[k] = append(m[k], v)
 		}
 	}