scons: Add warning for missing declarations

This patch enables warnings for missing declarations. To avoid issues
with SWIG-generated code, the warning is only applied to non-SWIG
code.

src/python/swig/pyobject.cc

@@ -35,10 +35,10 @@
 #include "base/inifile.hh"
 #include "base/output.hh"
 #include "dev/etherdevice.hh"
-#include "dev/etherint.hh"
 #include "dev/etherobject.hh"
 #include "mem/mem_object.hh"
 #include "mem/port.hh"
+#include "python/swig/pyobject.hh"
 #include "sim/full_system.hh"
 #include "sim/sim_object.hh"
 

src/python/swig/pyobject.hh

@@ -31,12 +31,15 @@
 #include <Python.h>
 
 #include "base/types.hh"
+#include "dev/etherint.hh"
 #include "sim/serialize.hh"
 #include "sim/sim_object.hh"
 
 extern "C" SimObject *convertSwigSimObjectPtr(PyObject *);
 SimObject *resolveSimObject(const std::string &name);
 
+EtherInt * lookupEthPort(SimObject *so, const std::string &name, int i);
+
 /**
  * Connect the described MemObject ports.  Called from Python via SWIG.
  */