* Makefile.in (ALLDEPFILES): Add alpha-osf1-tdep.c.

* Makefile.in (ALLDEPFILES): Add alpha-osf1-tdep.c.
(alpha-osf1-tdep.o): New dependency list.
* alpha-tdep.h (gdbarch_tdep): Add dynamic_sigtramp_offset
and skip_sigtramp_frame members.
* alpha-linux-tdep.c: Include gdbcore.h.
(alpha_linux_sigtramp_offset): Change return type to LONGEST.
(alpha_linux_init_abi): Initialize tdep->dynamic_sigtramp_offset.
* alpha-osf1-tdep.c: New file.
* alpha-tdep.c (alpha_osf_skip_sigtramp_frame): Moved to
alpha-osf1-dep.c.
(alpha_frame_past_sigtramp_frame): New function.
(alpha_dynamic_sigtramp_offset): Ditto.
(alpha_proc_desc_is_dyn_sigtramp): Ditto.
(alpha_set_proc_desc_is_dyn_sigtramp): Ditto.
(ALPHA_PROC_SIGTRAMP_MAGIC): Define.
(push_sigtramp_desc): Use alpha_set_proc_desc_is_dyn_sigtramp.
(after_prologue): Use alpha_proc_desc_is_dyn_sigtramp.
(find_proc_desc): Use alpha_dynamic_sigtramp_offset.
(alpha_frame_chain): Use alpha_frame_past_sigtramp_frame.
(alpha_init_extra_frame_info): Use alpha_proc_desc_is_dyn_sigtramp.
(alpha_pop_frame): Use alpha_proc_desc_is_dyn_sigtramp.
(alpha_gdbarch_init): Initialize tdep->dynamic_sigtramp_offset
and tdep->skip_sigtramp_frame.  Set gdbarch_skip_trampoline_code
to find_solib_trampoline_target.
* config/alpha/alpha-osf1.mt (TDEPFILES): Add alpha-osf1-tdep.o.
* config/alpha/tm-alpha.h: Remove inclusion of regcache.h.
(SKIP_TRAMPOLINE_CODE): Remove.
(PROC_DESC_IS_DYN_SIGTRAMP): Ditto.
(SET_PROC_DESC_IS_DYN_SIGTRAMP): Ditto.
(DYNAMIC_SIGTRAMP_OFFSET): Ditto.
(FRAME_PAST_SIGTRAMP_FRAME): Ditto.
* config/alpha/tm-alphalinux.h (PROC_DESC_IS_DYN_SIGTRAMP): Remove.
(PROC_SIGTRAMP_MAGIC): Ditto.
(PROC_DESC_IS_DYN_SIGTRAMP): Ditto.
(SET_PROC_DESC_IS_DYN_SIGTRAMP): Ditto.
(SET_PROC_DESC_IS_DYN_SIGTRAMP): Ditto.
(DYNAMIC_SIGTRAMP_OFFSET): Ditto.
(FRAME_PAST_SIGTRAMP_FRAME): Ditto.