[LTO] Move ChangeLog.lto into the GCC sub directory

[Kazu Hirata]

Hi Mark and Andrew,

>>Then can at least the changelog be more consistent to always include the
>>full path or not because right now there are two entries, one with
>>the full path and the other without.
> 
> 
> Yes, you are correct; it should be consistent.  Kazu, would you please
> change your ChangeLog entry to use the full patch to tree-vect-transform.c?

Done.

Kazu Hirata