container/intsets: update build tags to exclude assembly from gccgo.

Change-Id: I6f3b351d42f5534dd5a5ff161f1e5680b4dbfd58
Reviewed-on: https://go-review.googlesource.com/16793
Reviewed-by: Andrew Gerrand <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>

Author: dsymonds

container/intsets/popcnt_amd64.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build amd64,!appengine
+// +build amd64,!appengine,!gccgo
 
 package intsets
 

container/intsets/popcnt_amd64.s

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build amd64,!appengine,!gccgo
+
 #include "textflag.h"
 
 // func havePOPCNT() bool

container/intsets/popcnt_generic.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !amd64 appengine
+// +build !amd64 appengine gccgo
 
 package intsets