* bidi.c: Use bool for boolean.

* bidi.c: Use bool for boolean.

This is a bit more readable, and makes the text segment of bidi.o
0.4% smaller on my platform (GCC 4.7.1 x86-64, Fedora 15).
Presumably it's faster too.
(bidi_initialized, bidi_ignore_explicit_marks_for_paragraph_level):
Now bool.
(bidi_cache_find_level_change, bidi_cache_iterator_state)
(bidi_unshelve_cache, bidi_init_it, bidi_count_bytes)
(bidi_char_at_pos, bidi_fetch_char, bidi_paragraph_init)
(bidi_explicit_dir_char, bidi_level_of_next_char)
(bidi_find_other_level_edge, bidi_move_to_visually_next):
Use bool for booleans, instead of int.
* dispextern.h (bidi_init_it, bidi_paragraph_init)
(bidi_unshelve_cache): Adjust decls to match code.