util: xleep for Windows.

Windows does not have a sleep(seconds). But it does have
a Sleep(milliseconds). Sleep() in windows does not have a
return value. Since we are not using the return value for xsleep()
anywhere as of now, don't return any.

Introduced by commit 275eebb9 (utils: Introduce xsleep for RCU quiescent state)

CC: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>
Acked-by: Pravin B Shelar <pshelar@nicira.com>

lib/util.c

@@ -1727,15 +1727,16 @@ exit:
     return ok;
 }
 
-unsigned int
+void
 xsleep(unsigned int seconds)
 {
-    unsigned int t;
-
     ovsrcu_quiesce_start();
-    t = sleep(seconds);
+#ifdef _WIN32
+    Sleep(seconds * 1000);
+#else
+    sleep(seconds);
+#endif
     ovsrcu_quiesce_end();
-    return t;
 }
 
 #ifdef _WIN32