* mipsnbsd-nat.c: Include "target.h" and "inf-ptrace.h".

* mipsnbsd-nat.c: Include "target.h" and "inf-ptrace.h".
(mipsnbsd_fetch_inferior_registers): Rename from
fetch_inferior_registers.  Make static.
(mipsnbsd_store_inferior_registers): Rename from
store_inferior_registers.  Make static.
(_initialize_mipsnbsd_nat): New function and prototype.
* Makefile.in (mipsnbsd-nat.o): Update dependencies.
* config/mips/nbsd.mh (NAT_CLIBS, NAT_FILE): Remove variables.
(NATDEPFILES): Remove infptrace.o and inftarg.o.  Add
inf-ptrace.o.