windows: don't check non-existent return code in GetStartupInfo

Same as CL 520275 did in package syscall.

For golang/go#31316

Change-Id: Ie9d8fed7f40b9e562534d5e91488b4ba1ac44f34
Reviewed-on: https://go-review.googlesource.com/c/sys/+/520295
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>

windows/syscall_windows.go

@@ -216,7 +216,7 @@ func NewCallbackCDecl(fn interface{}) uintptr {
 //sys	shGetKnownFolderPath(id *KNOWNFOLDERID, flags uint32, token Token, path **uint16) (ret error) = shell32.SHGetKnownFolderPath
 //sys	TerminateProcess(handle Handle, exitcode uint32) (err error)
 //sys	GetExitCodeProcess(handle Handle, exitcode *uint32) (err error)
-//sys	GetStartupInfo(startupInfo *StartupInfo) (err error) = GetStartupInfoW
+//sys	getStartupInfo(startupInfo *StartupInfo) = GetStartupInfoW
 //sys	GetProcessTimes(handle Handle, creationTime *Filetime, exitTime *Filetime, kernelTime *Filetime, userTime *Filetime) (err error)
 //sys	DuplicateHandle(hSourceProcessHandle Handle, hSourceHandle Handle, hTargetProcessHandle Handle, lpTargetHandle *Handle, dwDesiredAccess uint32, bInheritHandle bool, dwOptions uint32) (err error)
 //sys	WaitForSingleObject(handle Handle, waitMilliseconds uint32) (event uint32, err error) [failretval==0xffffffff]
@@ -1628,6 +1628,11 @@ func SetConsoleCursorPosition(console Handle, position Coord) error {
 	return setConsoleCursorPosition(console, *((*uint32)(unsafe.Pointer(&position))))
 }
 
+func GetStartupInfo(startupInfo *StartupInfo) error {
+	getStartupInfo(startupInfo)
+	return nil
+}
+
 func (s NTStatus) Errno() syscall.Errno {
 	return rtlNtStatusToDosErrorNoTeb(s)
 }

windows/syscall_windows_test.go

@@ -1173,3 +1173,12 @@ func TestTimePeriod(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestGetStartupInfo(t *testing.T) {
+	var si windows.StartupInfo
+	err := windows.GetStartupInfo(&si)
+	if err != nil {
+		// see https://go.dev/issue/31316
+		t.Fatalf("GetStartupInfo: got error %v, want nil", err)
+	}
+}