Fixes for compilation under IRIX, submitted by Randal Hopper, with mods

from Robert.

include/osg/FrameStamp

@@ -7,7 +7,12 @@
 
 #include <osg/Referenced>
 
+#ifdef __sgi
+#include <time.h>
+#else
 #include <ctime>
+using std::tm;
+#endif
 
 namespace osg
 {

include/osg/Timer

@@ -132,7 +132,7 @@ namespace osg{
         }
         else
         {
-            return *_sgiClockAddress;
+            return *_clockAddress;
         }
     }
 };