cmd/compile/internal/ssa: hide gen packge from ./make.bash

Fixes #15122

Change-Id: Ie2c802d78aea731e25bf4b193b3c2e4c884e0573
Reviewed-on: https://go-review.googlesource.com/21524
Run-TryBot: Dave Cheney <dave@cheney.net>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/compile/internal/ssa/gen/AMD64Ops.go

@@ -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 ignore
+
 package main
 
 import "strings"

src/cmd/compile/internal/ssa/gen/ARMOps.go

@@ -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 ignore
+
 package main
 
 func init() {

src/cmd/compile/internal/ssa/gen/decOps.go

@@ -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 ignore
+
 package main
 
 var decOps = []opData{}

src/cmd/compile/internal/ssa/gen/genericOps.go

@@ -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 ignore
+
 package main
 
 // Generic opcodes typically specify a width. The inputs and outputs

src/cmd/compile/internal/ssa/gen/main.go

@@ -2,9 +2,10 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build ignore
+
 // The gen command generates Go code (in the parent directory) for all
 // the architecture-specific opcodes, blocks, and rewrites.
-
 package main
 
 import (

src/cmd/compile/internal/ssa/gen/rulegen.go

@@ -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 gen
+
 // This program generates Go code that applies rewrite rules to a Value.
 // The generated code implements a function of type func (v *Value) bool
 // which returns true iff if did something.