Obsolete old m68k systems.
* configure.host: Mark m68*-sun-*, m68*-sun-sunos4*,
m68*-sun-sunos3*, m68*-motorola-*, m68*-*-sysv4*, m68*-*-lynxos*,
m68*-bull*-sysv*, m68*-att-*, m680[01]0-sun-sunos4*, and
m680[01]0-sun-sunos3* as obsolete.
* configure.tgt: Mark m68*-*-lynxos*, m68*-*-sunos3*,
m68*-*-sunos4*, m68*-*-sysv4*, m68000-*-sunos3*, m68000-*-sunos4*,
m68*-bull-sysv*, m68*-att-*, and m68*-motorola-*, as obsolete.
* config/m68k/sun3os4.mh: Mark file obsolete.
* config/m68k/xm-sun3os4.h: Mark file obsolete.
* config/m68k/sun3os3.mh: Mark file obsolete.
* config/m68k/nm-sun3.h: Mark file obsolete.
* config/m68k/xm-sun3.h: Mark file obsolete.
* config/m68k/sun2os4.mh: Mark file obsolete.
* config/m68k/sun2os3.mh: Mark file obsolete.
* config/m68k/nm-sun2.h: Mark file obsolete.
* config/m68k/xm-sun2.h: Mark file obsolete.
* config/m68k/m68kv4.mh: Mark file obsolete.
* config/m68k/nm-sysv4.h: Mark file obsolete.
* config/m68k/xm-m68kv4.h: Mark file obsolete.
* config/m68k/m68klynx.mh: Mark file obsolete.
* config/m68k/nm-m68klynx.h: Mark file obsolete.
* config/m68k/dpx2.mh: Mark file obsolete.
* config/m68k/xm-dpx2.h: Mark file obsolete.
* config/m68k/nm-dpx2.h: Mark file obsolete.
* config/m68k/delta68.mh: Mark file obsolete.
* config/m68k/xm-delta68.h: Mark file obsolete.
* config/m68k/nm-delta68.h: Mark file obsolete.
* config/m68k/3b1.mh: Mark file obsolete.
* config/m68k/xm-3b1.h: Mark file obsolete.
* config/m68k/sun3os4.mt: Mark file obsolete.
* config/m68k/tm-sun3os4.h: Mark file obsolete.
* config/m68k/sun3os3.mt: Mark file obsolete.
* config/m68k/tm-sun3.h: Mark file obsolete.
* config/m68k/sun2os4.mt: Mark file obsolete.
* config/m68k/tm-sun2os4.h: Mark file obsolete.
* config/m68k/sun2os3.mt: Mark file obsolete.
* config/m68k/tm-sun2.h: Mark file obsolete.
* config/m68k/m68kv4.mt: Mark file obsolete.
* config/m68k/tm-m68kv4.h: Mark file obsolete.
* config/m68k/m68klynx.mt: Mark file obsolete.
* config/m68k/tm-m68klynx.h: Mark file obsolete.
* config/m68k/dpx2.mt: Mark file obsolete.
* config/m68k/tm-dpx2.h: Mark file obsolete.
* config/m68k/delta68.mt: Mark file obsolete.
* config/m68k/tm-delta68.h: Mark file obsolete.
* config/m68k/3b1.mt: Mark file obsolete.
* config/m68k/tm-3b1.h: Mark file obsolete.
* d10v-tdep.c (d10v_frame_chain_valid): Remove unnecessary tests.
* hppa-tdep.c (hppa_frame_chain_valid): Remove unnecessary test.
* blockframe.c: Include "gdbcmd.h" and "command.h".
(backtrace_below_main): New variable.
(file_frame_chain_valid, func_frame_chain_valid)
(nonnull_frame_chain_valid, generic_file_frame_chain_valid)
(generic_func_frame_chain_valid): Remove functions.
(frame_chain_valid, do_flush_frames_sfunc): New functions.
(_initialize_blockframe): New function.
* Makefile.in (blockframe.o): Update dependencies.
* frame.c (frame_saved_regs_id_unwind, get_prev_frame): Remove FIXME
comment. Call frame_chain_valid ().
* frame.h: Remove old prototypes. Add prototype for
frame_chain_valid and update comments to match.
* gdbarch.sh: Change FRAME_CHAIN_VALID into a predicated function.
Remove old comment.
* gdbarch.h: Regenerated.
* gdbarch.c: Regenerated.
Plus updates to all other targets not to provide a FRAME_CHAIN_VALID.