Adding GLU to the OPENGL_LIBRARIES only if it is found.

Modules/FindOpenGL.cmake

@@ -121,14 +121,16 @@ IF(OPENGL_INCLUDE_DIR)
       SET( OPENGL_XMESA_FOUND "NO" )
     ENDIF(OPENGL_xmesa_INCLUDE_DIR)
 
+    SET( OPENGL_LIBRARIES  ${OPENGL_gl_LIBRARY} ${OPENGL_LIBRARIES})
     IF(OPENGL_glu_LIBRARY)
       SET( OPENGL_GLU_FOUND "YES" )
-    ENDIF(OPENGL_glu_LIBRARY)
+      SET( OPENGL_LIBRARIES ${OPENGL_glu_LIBRARY} ${OPENGL_LIBRARIES} )
+    ELSE(OPENGL_glu_LIBRARY)
       SET( OPENGL_GLU_FOUND "NO" )
     ENDIF(OPENGL_glu_LIBRARY)
 
     SET( OPENGL_FOUND "YES" )
-    SET( OPENGL_LIBRARIES  ${OPENGL_glu_LIBRARY} ${OPENGL_gl_LIBRARY} ${OPENGL_LIBRARIES})
+    
 
 #The following deprecated settings are for backwards compatibility with CMake1.4
     SET (OPENGL_LIBRARY ${OPENGL_LIBRARIES})