[x86] Fix register constraints for multiply-high.

test/mjsunit/compiler/regress-register-allocator.js

+// Copyright 2014 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+function Module(stdlib, foreign, buffer) {
+  "use asm";
+  var HEAP32 = new stdlib.Int32Array(buffer);
+  function g(a) {
+    HEAP32[a] = 9982 * 100;
+    return a;
+  }
+  function f(i1) {
+    i1 = i1 | 0;
+    var i2 = HEAP32[i1 >> 2] | 0;
+    g(i1);
+    L2909: {
+      L2: {
+        if (0) {
+          if (0) break L2;
+          g(i2);
+          break L2909;
+        }
+      }
+      var r = (HEAP32[1] | 0) / 100 | 0;
+      g(r);
+      return r;
+    }
+  }
+  return {f: f};
+}
+
+var f = Module(this, {}, new ArrayBuffer(64 * 1024)).f;
+assertEquals(9982, f(1));