build: add -buildmode to cross-compile.go

This builds on

768e4c4735 build: Temporary fix for Windows build errors

But passes the -buildmode flag down to the cross-compile.go command
too.

bin/cross-compile.go

@@ -36,6 +36,7 @@ var (
 	cgo         = flag.Bool("cgo", false, "Use cgo for the build")
 	noClean     = flag.Bool("no-clean", false, "Don't clean the build directory before running.")
 	tags        = flag.String("tags", "", "Space separated list of build tags")
+	buildmode   = flag.String("buildmode", "", "Passed to go build -buildmode flag")
 	compileOnly = flag.Bool("compile-only", false, "Just build the binary, not the zip.")
 )
 
@@ -300,8 +301,15 @@ func compileArch(version, goos, goarch, dir string) bool {
 		"-trimpath",
 		"-o", output,
 		"-tags", *tags,
-		"..",
 	}
+	if *buildmode != "" {
+		args = append(args,
+			"-buildmode", *buildmode,
+		)
+	}
+	args = append(args,
+		"..",
+	)
 	env := []string{
 		"GOOS=" + goos,
 		"GOARCH=" + stripVersion(goarch),