windows: add GetFileTime

Add a simple Windows API GetFileTime.
The document is https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-getfiletime

Fixes golang/go#21541

Change-Id: Ia7b8385d27348b2abc0ee560c5bd7e66cb6d13f2
GitHub-Last-Rev: 6700dcc
GitHub-Pull-Request: #174
Reviewed-on: https://go-review.googlesource.com/c/sys/+/528015
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>

windows/syscall_windows.go

@@ -233,6 +233,7 @@ func NewCallbackCDecl(fn interface{}) uintptr {
 //sys	CreateEnvironmentBlock(block **uint16, token Token, inheritExisting bool) (err error) = userenv.CreateEnvironmentBlock
 //sys	DestroyEnvironmentBlock(block *uint16) (err error) = userenv.DestroyEnvironmentBlock
 //sys	getTickCount64() (ms uint64) = kernel32.GetTickCount64
+//sys   GetFileTime(handle Handle, ctime *Filetime, atime *Filetime, wtime *Filetime) (err error)
 //sys	SetFileTime(handle Handle, ctime *Filetime, atime *Filetime, wtime *Filetime) (err error)
 //sys	GetFileAttributes(name *uint16) (attrs uint32, err error) [failretval==INVALID_FILE_ATTRIBUTES] = kernel32.GetFileAttributesW
 //sys	SetFileAttributes(name *uint16, attrs uint32) (err error) = kernel32.SetFileAttributesW