Replace system_nosh call with android_fork_execvp

Replace the system_nosh call with the android_fork_execvp from
liblogwrap.

Change-Id: Idfbc6bcf0bef16d4ee90d6af6bd4b07bc79913bb
diff --git a/IdletimerController.h b/IdletimerController.h
index eb2aa35..98a312e 100644
--- a/IdletimerController.h
+++ b/IdletimerController.h
@@ -36,7 +36,7 @@
  private:
     enum IptOp { IptOpAdd, IptOpDelete };
     int setDefaults();
-    int runIpxtablesCmd(const char *cmd);
+    int runIpxtablesCmd(int argc, const char **cmd);
     int modifyInterfaceIdletimer(IptOp op, const char *iface, uint32_t timeout,
                                  const char *classLabel);
 };