Make some member functions const

include/wx/process.h

@@ -167,10 +167,10 @@ public:
 
     // accessors
         // PID of process which terminated
-    int GetPid() { return m_pid; }
+    int GetPid() const { return m_pid; }
 
         // the exit code
-    int GetExitCode() { return m_exitcode; }
+    int GetExitCode() const { return m_exitcode; }
 
     // implement the base class pure virtual
     virtual wxEvent *Clone() const wxOVERRIDE { return new wxProcessEvent(*this); }