Add stub impl of virNetlinkEventServiceLocalPid for Win32

The libvirt_private.syms file exports virNetlinkEventServiceLocalPid
so there needs to be a no-op stub for Win32 to avoid linker errors
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit 2d191e8e)

src/util/virnetlink.c

@@ -659,6 +659,12 @@ bool virNetlinkEventServiceIsRunning(void)
     return 0;
 }
 
+int virNetlinkEventServiceLocalPid(void)
+{
+    netlinkError(VIR_ERR_INTERNAL_ERROR, "%s", _(unsupported));
+    return -1;
+}
+
 /**
  * virNetlinkEventAddClient: register a callback for handling of
  * netlink messages