Fix Go template script escaping

Fixes #6695

tpl/internal/go_templates/cfg/cfg.go

@@ -0,0 +1,64 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package cfg holds configuration shared by the Go command and internal/testenv.
+// Definitions that don't need to be exposed outside of cmd/go should be in
+// cmd/go/internal/cfg instead of this package.
+package cfg
+
+// KnownEnv is a list of environment variables that affect the operation
+// of the Go command.
+const KnownEnv = `
+	AR
+	CC
+	CGO_CFLAGS
+	CGO_CFLAGS_ALLOW
+	CGO_CFLAGS_DISALLOW
+	CGO_CPPFLAGS
+	CGO_CPPFLAGS_ALLOW
+	CGO_CPPFLAGS_DISALLOW
+	CGO_CXXFLAGS
+	CGO_CXXFLAGS_ALLOW
+	CGO_CXXFLAGS_DISALLOW
+	CGO_ENABLED
+	CGO_FFLAGS
+	CGO_FFLAGS_ALLOW
+	CGO_FFLAGS_DISALLOW
+	CGO_LDFLAGS
+	CGO_LDFLAGS_ALLOW
+	CGO_LDFLAGS_DISALLOW
+	CXX
+	FC
+	GCCGO
+	GO111MODULE
+	GO386
+	GOARCH
+	GOARM
+	GOBIN
+	GOCACHE
+	GOENV
+	GOEXE
+	GOFLAGS
+	GOGCCFLAGS
+	GOHOSTARCH
+	GOHOSTOS
+	GOINSECURE
+	GOMIPS
+	GOMIPS64
+	GOMODCACHE
+	GONOPROXY
+	GONOSUMDB
+	GOOS
+	GOPATH
+	GOPPC64
+	GOPRIVATE
+	GOPROXY
+	GOROOT
+	GOSUMDB
+	GOTMPDIR
+	GOTOOLDIR
+	GOWASM
+	GO_EXTLINK_ENABLED
+	PKG_CONFIG
+`