var go/build.installgoroot

3 uses

	go/build (current package)
		build.go#L559: var installgoroot = godebug.New("installgoroot")
		build.go#L823: 			if !p.Goroot || (installgoroot.Value() == "all" && p.ImportPath != "unsafe" && p.ImportPath != "builtin") {
		build.go#L825: 					installgoroot.IncNonDefault()