Don't put chars into lower case when searching in announce.
#1J9zhBw0 (SYSOP) [ptt.cc]

We already have DBCS_strcasestr.


git-svn-id: http://opensvn.csie.org/pttbbs/trunk@5950 63ad8ddf-47c3-0310-b6dd-a9e9d9715204