util/winutil: add RegisterForRestart, allowing programs to indicate their preferences to the Windows restart manager

In order for the installer to restart the GUI correctly post-upgrade, we
need the GUI to be able to register its restart preferences.

This PR adds API support for doing so. I'm adding it to OSS so that it
is available should we need to do any such registrations on OSS binaries
in the future.

Updates https://github.com/tailscale/corp/issues/13998

Signed-off-by: Aaron Klotz <aaron@tailscale.com>

util/winutil/zsyscall_windows.go

@@ -6,6 +6,7 @@ import (
 	"syscall"
 	"unsafe"
 
+	"github.com/dblohm7/wingoes"
 	"golang.org/x/sys/windows"
 )
 
@@ -39,8 +40,10 @@ func errnoErr(e syscall.Errno) error {
 
 var (
 	modadvapi32 = windows.NewLazySystemDLL("advapi32.dll")
+	modkernel32 = windows.NewLazySystemDLL("kernel32.dll")
 
-	procQueryServiceConfig2W = modadvapi32.NewProc("QueryServiceConfig2W")
+	procQueryServiceConfig2W       = modadvapi32.NewProc("QueryServiceConfig2W")
+	procRegisterApplicationRestart = modkernel32.NewProc("RegisterApplicationRestart")
 )
 
 func queryServiceConfig2(hService windows.Handle, infoLevel uint32, buf *byte, bufLen uint32, bytesNeeded *uint32) (err error) {
@@ -50,3 +53,9 @@ func queryServiceConfig2(hService windows.Handle, infoLevel uint32, buf *byte, b
 	}
 	return
 }
+
+func registerApplicationRestart(cmdLineExclExeName *uint16, flags uint32) (ret wingoes.HRESULT) {
+	r0, _, _ := syscall.Syscall(procRegisterApplicationRestart.Addr(), 2, uintptr(unsafe.Pointer(cmdLineExclExeName)), uintptr(flags), 0)
+	ret = wingoes.HRESULT(r0)
+	return
+}