fixed minor bug of strcasestr
fixed minor bug of strcasestr

- use upper case instead lower case for int18n
- add islower check before convert

Review-URL: https://codereview.appspot.com/269800043

code4bones/drmemory,code4bones/drmemory,code4bones/drmemory,code4bones/drmemory,code4bones/drmemory