target_op(..) -> target_op(target, ...) obvious

[Andrew Cagney]

> As part of the on-going OO of GDB, the "target vector" is one of the next things up for treatment.  I'd like to be sure that everyones ok with the mechanical transformatioin:
> 
>     target_OP (...) -> taget_OP (target, ...)
> 
> being considered "fairly obvious" (post patch, give it a few days, commit patch).  Pushing the target around is going to involve touching files across maintenance boundraries.

[Not my day.]

The rationale is the same as for the architecture vector along with the 
push to eliminate global thread/frame state.  It is to make it possible 
to have multiple instances of a specific target.  For instance,two 
ptrace inferior's, or two active remotes.

Andrew