File tools-packaging.patch of Package go1.10

Index: go/src/cmd/go/internal/load/pkg.go
===================================================================
--- go.orig/src/cmd/go/internal/load/pkg.go
+++ go/src/cmd/go/internal/load/pkg.go
@@ -964,7 +964,13 @@ func (p *Package) load(stk *ImportStack,
 		if InstallTargetDir(p) == ToTool {
 			// This is for 'go tool'.
 			// Override all the usual logic and force it into the tool directory.
-			p.Target = filepath.Join(cfg.GOROOTpkg, "tool", full)
+			// If GOROOT_TARGET is set, then write to it for packaging purpose
+			gorootTarget := os.Getenv("GOROOT_TARGET")
+			if gorootTarget == "" {
+				p.Target = filepath.Join(cfg.GOROOTpkg, "tool", full)
+			} else {
+				p.Target = filepath.Join(gorootTarget, "pkg/tool", full)
+			}
 		}
 		if p.Target != "" && cfg.BuildContext.GOOS == "windows" {
 			p.Target += ".exe"