sg_netChat: let getTerminator return const char* for compatiblity with FlightGear

simgear/io/sg_netChat.cxx

@@ -37,10 +37,10 @@ NetChat::setTerminator(const std::string& t)
   bytesToCollect = -1;
 }
 
-const std::string&
+const char*
 NetChat::getTerminator() const
 {
-  return terminator;
+  return terminator.c_str();
 }
 
 

simgear/io/sg_netChat.hxx

@@ -79,7 +79,7 @@ public:
   {}
 
   void setTerminator(const std::string& t);
-  const std::string& getTerminator() const;
+  const char* getTerminator() const;
 
   /**
    * set byte count to collect - 'foundTerminator' will be called once