Optimize exclude: use hash tables for non-wildcard patterns.

Optimize exclude: use hash tables for non-wildcard patterns.

* lib/exclude.c: Include hash.h and mbuiter.h
(struct exclude_pattern, exclude_segment): New data types.
(struct exclude): Rewrite.
(fnmatch_pattern_has_wildcards): New function.
(new_exclude_segment, free_exclude_segment): New functions.
(excluded_file_pattern_p, excluded_file_name_p): New functions.
(excluded_file_name, add_exclude): Rewrite using new struct exclude.
* lib/exclude.h (is_fnmatch_pattern): New prototype.
* modules/exclude: Depend on hash and mbuiter.

* modules/exclude-tests: New file.
* tests/test-exclude.c: New file.
* tests/test-exclude1.sh: New file.
* tests/test-exclude2.sh: New file.
* tests/test-exclude3.sh: New file.
* tests/test-exclude4.sh: New file.
* tests/test-exclude5.sh: New file.
* tests/test-exclude6.sh: New file.
* tests/test-exclude7.sh: New file.