* alpha-tdep.h (gdbarch_tdep): Add jb_pc and jb_elt_size members.

* alpha-tdep.h (gdbarch_tdep): Add jb_pc and jb_elt_size members.
* alpha-linux-tdep.c (alpha_linux_init_abi): Initialize
tdep->jb_pc and tdep->jb_elt_size.
* alpha-osf1-tdep.c (alpha_osf1_init_abi): Likewise.
* alphafbsd-tdep.c (alphafbsd_init_abi): Likewise.
* alphanbsd-tdep.c (alphanbsd_init_abi): Likewise.
* alpha-nat.c (get_longjmp_target): Remove.
(JB_ELEMENT_SIZE): Ditto.
(JB_PC): Ditto.
* alpha-tdep.c (alpha_get_longjmp_target): New function.
(alpha_gdbarch_init): Default tdep->jb_pc to -1.  If the
OS ABI sets jb_pc to a valid value, set gdbarch_get_longjmp_target
to alpha_get_longjmp_target.
(alpha_dump_tdep): Report tdep->jb_pc and tdep->jb_elt_size.
* config/alpha/nm-linux.h (GET_LONGJMP_TARGET): Remove.
* config/alpha/nm-osf.h (GET_LONGJMP_TARGET): Remove.