windows: remove repetitive words

Change-Id: I9c944eca6117b1039f0c5287706cb447b75c8cbd
Reviewed-on: https://go-review.googlesource.com/c/sys/+/509835
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>

windows/syscall_windows.go

@@ -135,14 +135,14 @@ func Getpagesize() int { return 4096 }
 
 // NewCallback converts a Go function to a function pointer conforming to the stdcall calling convention.
 // This is useful when interoperating with Windows code requiring callbacks.
-// The argument is expected to be a function with with one uintptr-sized result. The function must not have arguments with size larger than the size of uintptr.
+// The argument is expected to be a function with one uintptr-sized result. The function must not have arguments with size larger than the size of uintptr.
 func NewCallback(fn interface{}) uintptr {
 	return syscall.NewCallback(fn)
 }
 
 // NewCallbackCDecl converts a Go function to a function pointer conforming to the cdecl calling convention.
 // This is useful when interoperating with Windows code requiring callbacks.
-// The argument is expected to be a function with with one uintptr-sized result. The function must not have arguments with size larger than the size of uintptr.
+// The argument is expected to be a function with one uintptr-sized result. The function must not have arguments with size larger than the size of uintptr.
 func NewCallbackCDecl(fn interface{}) uintptr {
 	return syscall.NewCallbackCDecl(fn)
 }