gdb/
* frame.c (frame_stop_reason_string): Rewrite using
unwind_stop_reasons.def.
* frame.h (enum unwind_stop_reason): Likewise.
* python/py-frame.c (gdbpy_initialize_frames): Likewise.
(gdbpy_frame_stop_reason_string): Use new enum unwind_stop_reason
constants for bound-checking.
* unwind_stop_reasons.def: New file.
* stack.c (backtrace_command_1): Handle UNWIND_FIRST_ERROR as an alias
instead of a distinct value.
doc/
* gdb.texinfo ((Frames In Python): Document
gdb.FRAME_UNWIND_FIRST_ERROR contant.
