[ros-diffs] [weiden] 16859: added a forward declaration to _DRIVE_LAYOUT_INFORMATION(_EX). this fixes building io/disk.c with GCC4. The reason is that the structures were used in function prototypes, which are forward declarations in the scope of the function declaration only. Since the structures were defined later, the implementations of the functions using them, actually used the defined structure types, which were different from the forward declarations in the function prototypes (even though they have