cmd/go: install new5l etc to tool dir

Change-Id: I77ab2bed5884b0763147703fd976d462d036336d
Reviewed-on: https://go-review.googlesource.com/6334Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>

src/cmd/go/pkg.go

@@ -406,6 +406,10 @@ var goTools = map[string]targetDir{
 	"cmd/dist":                             toTool,
 	"cmd/fix":                              toTool,
 	"cmd/link":                             toTool,
+	"cmd/new5l":                            toTool,
+	"cmd/new6l":                            toTool,
+	"cmd/new8l":                            toTool,
+	"cmd/new9l":                            toTool,
 	"cmd/nm":                               toTool,
 	"cmd/objdump":                          toTool,
 	"cmd/pack":                             toTool,