region-cache.c, scroll.c, search.c: Use bool for booleans.

region-cache.c, scroll.c, search.c: Use bool for booleans.

* lisp.h (compile_pattern):
* scroll.c (do_scrolling, do_direct_scrolling):
* search.c (struct regexp_cache, compile_pattern_1)
(compile_pattern, string_match_1, search_command)
(trivial_regexp_p, search_buffer, Freplace_match, match_limit)
(search_regs_saved, Fregexp_quote):
Use bool for boolean.
* region-cache.c (region_cache_forward, region_cache_backward):
Fix comments to match code: these functions return int, not boolean.