Add another overload for sg_io_exception ctor.

simgear/structure/exception.cxx

@@ -260,6 +260,14 @@ sg_io_exception::sg_io_exception (const string& message, const string& origin)
 {
 }
 
+sg_io_exception::sg_io_exception (const string& message,
+				  const sg_location &location,
+				  const string& origin)
+  : sg_exception(message, origin),
+    _location(location)
+{
+}
+
 sg_io_exception::~sg_io_exception () throw ()
 {
 }

simgear/structure/exception.hxx

@@ -133,6 +133,9 @@ public:
   sg_io_exception (const char* message, const sg_location &location,
 		   const char* origin = 0);
   sg_io_exception (const std::string &message, const std::string &origin = "");
+  sg_io_exception (const std::string &message, const sg_location &location, 
+    const std::string &origin = "");
+  
   virtual ~sg_io_exception () throw ();
   virtual const std::string getFormattedMessage () const;
   virtual const sg_location &getLocation () const;