iterate return values

[Hollis Blanchard]

I'm having trouble seeing my Apple-partitioned disk with pc.mod loaded. 
The trouble seems to be a misunderstanding about how iterate methods 
should return.

When a hook is passed to grub_partition_iterate, it is applied to 
partmap->iterate. However, the partition map's iterate functions can 
return non-zero in case of error (such as "not a PC partition map"). 
Non-zero is then propagated back to grub_partition_map_iterate, and the 
iteration stops. In that case we should clearly keep going to try 
another partition map type.

However, the other case is that the hook itself returned non-zero, 
indicating it wishes to stop the iteration. As far as I can see there 
is no way to distinguish this from the above case. Or are there 
actually any hooks that want to stop iteration? If not, the test in 
grub_partition_map_iterate can go. (But that doesn't seem to fix my 
problem either... sigh.)

-Hollis