* trad-frame.h: Update comments, a -1 .addr is reserved.
(trad_frame_value_p, trad_frame_addr_p): Declare.
(trad_frame_reg_p): Declare.
(trad_frame_set_value): Rename trad_frame_register_value.
(trad_frame_set_unknown): Declare.
* trad-frame.c (trad_frame_realreg_p): New function.
(trad_frame_addr_p, trad_frame_value_p): New function.
(trad_frame_set_unknown): New function.
(trad_frame_alloc_saved_regs): Initialize .addr to -1, not zero.
(trad_frame_prev_register): Use trad_frame_realreg_p,
trad_frame_addr_p and trad_frame_value_p.
(trad_frame_set_value): Rename trad_frame_register_value.
* d10v-tdep.c (d10v_frame_unwind_cache): Use trad_frame_addr_p
and trad_frame_set_value.