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/cpu/legiontrace.hh

@@ -42,6 +42,8 @@ class ThreadContext;
 
 namespace Trace {
 
+void setupSharedData();
+
 class LegionTraceRecord : public InstRecord
 {
   public:

src/cpu/pc_event.hh

@@ -39,6 +39,7 @@
 
 class ThreadContext;
 class PCEventQueue;
+class System;
 
 class PCEvent
 {
@@ -141,4 +142,8 @@ class BreakPCEvent : public PCEvent
     virtual void process(ThreadContext *tc);
 };
 
+void sched_break_pc_sys(System *sys, Addr addr);
+
+void sched_break_pc(Addr addr);
+
 #endif // __PC_EVENT_HH__