updated for version 7.3.1153
Problem:    New regexp engine: Some look-behind matches are very expensive.
Solution:   Pospone invisible matches further, until a match is almost found.
Added tag v7-3-1153 for changeset bc3f4804cf47
updated for version 7.3.1154
Problem:    New regexp_nfa engine: Uneccessary code.
Solution:   Remove uneccessary code.
Added tag v7-3-1154 for changeset 6419ee8098c8
updated for version 7.3.1155
Problem:    MS-DOS: "make test" uses external rmdir command.
Solution:   Rename "rmdir" to "rd". (Taro Muraoka)
Added tag v7-3-1155 for changeset bf1e6326df11