windows: Provide a cancellable usleep(), but with ms resolution only

src/libstrongswan/utils/windows.c

@@ -36,6 +36,19 @@ void windows_deinit()
 	WSACleanup();
 }
 
+/**
+ * See header
+ */
+int usleep(useconds_t usec)
+{
+	if (usec > 0 && usec < 1000)
+	{	/* do not Sleep(0) for small values */
+		usec = 1000;
+	}
+	SleepEx(usec / 1000, TRUE);
+	return 0;
+}
+
 /**
  * See header
  */

src/libstrongswan/utils/windows.h

@@ -85,6 +85,11 @@ static inline int sleep(unsigned int seconds)
 	return 0;
 }
 
+/**
+ * Replacement of usleep(3), cancellable, ms resolution only
+ */
+int usleep(useconds_t usec);
+
 /**
  * strdup(3), the Windows variant can't free(strdup("")) and others
  */