Set Setpgid on child git processes (#19865)

When Gitea is running as PID 1 git will occassionally orphan child processes leading
to (defunct) processes. This PR simply sets Setpgid to true on these child processes
meaning that these defunct processes will also be correctly reaped.

Fix #19077

Signed-off-by: Andrew Thornton <art27@cantab.net>

modules/process/manager_windows.go

@@ -0,0 +1,16 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+//go:build windows
+
+package process
+
+import (
+	"os/exec"
+)
+
+// SetSysProcAttribute sets the common SysProcAttrs for commands
+func SetSysProcAttribute(cmd *exec.Cmd) {
+	// Do nothing
+}