Trigger read error handling if len is <= 0.

Red Hat Bug 494245 <https://bugzilla.redhat.com/show_bug.cgi?id=494245>

Reported-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
(cherry picked from commit 98ecb5233b)

src/evdev.c

@@ -564,7 +564,7 @@ EvdevReadInput(InputInfoPtr pInfo)
     while (len == sizeof(ev))
     {
         len = read(pInfo->fd, &ev, sizeof(ev));
-        if (len == 0)
+        if (len <= 0)
         {
             if (errno == ENODEV) /* May happen after resume */
             {