Hi Kevin, 

In aix-thread.c there are some obsolete and/or dubious uses of the
register cache (including direct reading/writing to the register cache).
This patch (which I emphasize, I have not tested!)
cleans them up and/or re-writes some of them.

Short summary: target_store_registers should copy the register cache
into the child's register state, but not by reading from the registers
array directly, and not by calling read_register.  The API for the 
target layer to get the contents of the cache is register_collect().
I also replaced a call to read_register_bytes from ops_prepare_to_store.

Michael