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/NatController.h b/NatController.h
index c1979bb..4330567 100644
--- a/NatController.h
+++ b/NatController.h
@@ -39,7 +39,7 @@
     SecondaryTableController *secondaryTableCtrl;
 
     int setDefaults();
-    int runCmd(const char *path, const char *cmd);
+    int runCmd(int argc, const char **argv);
     bool checkInterface(const char *iface);
     int setForwardRules(bool set, const char *intIface, const char *extIface);
 };