these files require. Dunno why my build didn't pick up the transitive
dependency.
# include <config.h>
#endif
+#include <GL/glu.h>
+
#include <simgear/props/props.hxx>
#include <Include/general.hxx>
# include <windows.h>
#endif
+#include <GL/glu.h>
+
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stdio.h> // char related functions
#include <string.h> // strcmp()
+#include <GL/glu.h>
+
#include <simgear/constants.h>
#include <simgear/debug/logstream.hxx>
#include <simgear/props/props.hxx>
#include <stdio.h> // sprintf
#include <string.h>
+#include <GL/glu.h>
+
#include <plib/ssg.h>
#include <plib/fnt.h>