Fix OpenBSD/i386 sigtramp recognition.

* i386-tdep.h: Update copyright year.
(i386bsd_pc_in_sigtramp, i386bsd_sigtramp_start)
(i386bsd_sigtramp_end): New prototypes.
(i386fbsd_sigtramp_start_addr): Renamed from
i386fbsd_sigtramp_start.
(i386fbsd_sigtramp_end_addr): Renamed from i386fbsd_sigtramp_end.
(i386obsd_sigtramp_start_addr): Renamed from
i386obsd_sigtramp_start.
(i386obsd_sigtramp_end_addr): Renamed from i386obsd_sigtramp_end.
* i386bsd-tdep.c: Update copyright year.
(i386bsd_pc_in_sigtramp): Make public.
* i386fbsd-nat.c: Update copyright year.
(_initialize_i386fbsd_nat): Adjust for renamed variables.
* i386fbsd-tdep.c: Update copyright year.
(i386fbsd_sigtramp_start_addr): Renamed from
i386fbsd_sigtramp_start.
(i386fbsd_sigtramp_end_addr): Renamed from i386fbsd_sigtramp_end.
(i386fbsdaout_init_abi): Adjust for renamed variables.
* i386obsd-nat.c: Update copyright year.
(_initialize_i386obsd_nat): Adjust for renamed variables.
* i386obsd-tdep.c: Include "target.h".
(i386obsd_page_size): New variable.
(i386obsd_pc_in_sigtramp, i386obsd_sigtramp_start)
(i386obsd_sigtramp_end): New functions.
(i386obsd_sigtramp_start_addr): Renamed from
i386obsd_sigtramp_start.
(i386obsd_sigtramp_end_addr): Renamed from i386obsd_sigtramp_end.
(i386obsd_init_abi): Adjust for renamed variables.  Set
pc_in_sigtramp, sigtramp_start and sigtramp_end.
* Makefile.in (i386obsd-tdep.o): Update dependencies.