Fix use of int instead of EMACS_INT in search.c and region-cache.c.

Fix use of int instead of EMACS_INT in search.c and region-cache.c.

 indent.c (compute_motion): Use EMACS_INT for arguments to
 region_cache_forward.
 region-cache.c (struct boundary, struct region_cache): Use
 EMACS_INT for positions.
 (find_cache_boundary, move_cache_gap, insert_cache_boundary)
 (delete_cache_boundaries, set_cache_region)
 (invalidate_region_cache, know_region_cache)
 (region_cache_forward, region_cache_backward, pp_cache): Use
 EMACS_INT for buffer positions.
 region-cache.h (know_region_cache, invalidate_region_cache)
 (region_cache_forward, region_cache_backward): Adjust prototypes.
 search.c (string_match_1, fast_c_string_match_ignore_case)
 (looking_at_1, scan_buffer, scan_newline)
 (find_next_newline_no_quit, find_before_next_newline)
 (search_command, trivial_regexp_p, search_buffer, simple_search)
 (boyer_moore, wordify, Freplace_match): Use EMACS_INT for buffer
 and string positions and length.
 lisp.h (scan_buffer, scan_newline, find_next_newline_no_quit)
 (find_before_next_newline): Adjust prototypes.