* amd64obsd-tdep.c: Include "regset.h" and "i387-tdep.h". Fix

* amd64obsd-tdep.c: Include "regset.h" and "i387-tdep.h".  Fix
comments.
(amd64obsd_supply_regset, amd64obsd_regset_from_core_section): New
functions.
(amd64obsd_init_abi): Reorder initializations.  Use
amd64obsd_r_reg_offset to initialize the general-purpose register
set details.  Set regset_from_core_section.
(_initialize_amd64obsd_tdep): Rename from
_initialize_amd64obsd_ndep.  Add OS ABI handler for core dumps.
* Makefile.in (amd64obsd-tdep.o): Update dependencies.
* config/i386/obsd64.mt (TDEPFILES): Add i386-tdep.o.