Fix PR build/1549.

Fix PR build/1549.
* i386obsd-tdep.c: Update copyright years.  Include
"solib-svr4.h".
(i386obsd_init_abi): Don't set regset_from_core_section here.
(i386obsd_aout_init_abi): New function.  Set
regset_from_core_section here.
(i386obsd_elf_init_abi): New function.
(_initialize_i386obsd_tdep): Register OS/ABI for OpenBSD ELF.
* Makefile.in (i386obsd-tdep.o): Update dependecies.
* config/i386/obsd.mt (TDEPFILES): Add solib.o and solib-svr4.o.
(TM_FILE): Set to tm-nbsd.h.

* config/i386/obsd.mh (NATDEPFILES): Remove solib.o and
solib-sunos.o.