read_register() and write_register() on deprecate hit list

[Andrew Cagney]

FYI,

Having examined the cleaned up d10v, I've identified the methods:

read_register()
write_register()

as high on the deprecated hit list.  Both of these are implicitly 
relying on the global register cache :-(

As part of eliminating these, the inferior function call methods 
(SAVE_STRUCT_RETURN, PUSH_ARGS, ...) will need their interface modified 
so that they take an explicit regcache.

This is just a heads up so people know it is comming.  Schedule? ....

Andrew