[RFA] Remove KERNEL_U_ADDR from config/nm-nbsd.h

[Andrew Cagney]

> The following patch removes the definition of KERNEL_U_ADDR from
> the NetBSD native configs.
> 
> The reason for doing so: the definition is completely bogus.  NetBSD
> has not used the U-area for process or core file debugging for many
> many years, and the U-area isn't even double-mapped at a fixed address
> anymore (i.e. there is no "u.").
> 
> In addition, pulling in <machine/vmparam.h> (for the USRSTACK definition)
> on some targets causes a compilation error, since this file is not meant
> to be included directly (or by userland at all!).
> 
> 	* config/nm-nbsd.h (KERNEL_U_ADDR): Remove.


Ah.  Yes, approved.

Andrew