[patch/rfc, rfa:doco] Deprecate NPC_REGNUM

[Andrew Cagney]

> Hello,
> 
> Core GDB uses NPC_REGNUM in two ways:
> 
> - in generic write pc to upate the next pc
> Architectures (HP/UX and SPARC) can (and I suspect do) implement TARGET_WRITE_PC to do this directly
> 
> - procfs_fetch_registers contains the performance tweak:
>   if (FP0_REGNUM >= 0)  /* need floating point? */
>     {
>       if ((regno >= 0 && regno < FP0_REGNUM) ||
>           regno == PC_REGNUM  ||
>           (NPC_REGNUM >= 0 && regno == NPC_REGNUM) ||
>           regno == DEPRECATED_FP_REGNUM  ||
>           regno == SP_REGNUM)
>         return;                 /* not a floating point register */
> 
>       if ((fpregs = proc_get_fpregs (pi)) == NULL)
>         proc_error (pi, "fetch_registers, get_fpregs", __LINE__);
> 
>       supply_fpregset (fpregs);
>     }
> Even without NPC_REGNUM, GDB works.  The regset stuff should make it possible to both cleanup the code and rewrite that performance hack into oblivion.
> 
> Eli, doco ok?
> 
> I'll follow up in a few days,

FYI, I've checked in the code side of these changes.

Andrew