* m68knbsd-nat.c: Remove file.

* m68knbsd-nat.c: Remove file.
* m68knbsd-tdep.c: Remove file.
* Makefile.in: (m68knbsd-nat.o, m68knbsd-tdep.o): Remove
dependencies.
* configure.host: Add m68k-*-netbsdelf*.
* configure.tgt (m68k-*-netbsd*): Set gdb_target to nbsd.
* config/m68k/nbsdaout.mh (NATDEPFILES): Add m68kbsd-nat.o,
solib.o and solib-sunos.o.  Remove m68knbsd-nat.o, corelow.o.
(XM_FILE): Remove.
* config/m68k/nbsdelf.mh: New file.
* config/m68k/nbsd.mt: New file.
* config/m68k/nbsdaout.mt: Remove file.
* config/m68k/tm-nbsd.h: Don't include <sys/param.h>,
<machine/vmparam.h> and "m68k/tm-m68k.h".  Include "solib.h".
(BPT_VECTOR, STACK_END_ADDR): Remove defines.
(DEPRECATED_SIGTRAMP_START, DEPRECATED_SIGTRAMP_END): Likewise.
(use_struct_convention): Remove prototype.
(USE_STRUCT_CONVENTION): Remove define.
* config/m68k/xm-nbsd.h: Remove file.