* amd64-nat.h: New file.

* amd64-nat.h: New file.
* amd64-nat.c: New file.
* amd64fbsd-nat.c: Include "amd64-nat.h".
(REG_ADDR, GETREGS_SUPPLIES): Remove macros.
(amd64fbsd32_r_reg_offset): New variable.
(supply_gregset): Simply call amd64_supply_native_gregset.
(fill_gregset): Rename `regno' to `regnum'.  Simply call
amd64_collect_native_gregset.
(fill_fpregset): Rename `regno' to `regnum'.
(fetch_inferior_registers): Rename `regno' to `regnum'.  Replace
usage of GETREGS_SUPPLIES with amd64_native_gregset_supplies_p.
Use `struct reg' and `struct fpreg' instead of `gregset_t' and
`fpregset_t'.  Call amd64_supply_native_gregset instead of
supply_gregset.  Call x86_64_supply_fxsave instead of
supply_fpregset.
(store_inferior_registers): Rename `regno' to `regnum'.  Replace
usage of GETREGS_SUPPLIES with amd64_native_gregset_supplies_p.
Use `struct reg' and `struct fpreg' instead of `gregset_t' and
`fpregset_t'.  Call amd64_collect_native_gregset instead of
fill_gregset.  Call x86_64_collect_fxsave instead of
fill_fpregset.
(_initialize_am64fbsd_nat): Initialize
amd64_native_gregset32_reg_offset and
amd64_native_gregset64_reg_offset.
* config/i386/fbsd64.mh (NATDEPFILES): Add amd64-nat.o.