This patch fixes the failure caused by the
posix lseek and read versions under windows in cdf_read() .
Additionally all the occurences of lseek and read
was replaced by _lseek and _reed for windows.
- remove duplicate code (like mime_content_type() compatibility function
now use the same base as finfo_file())
- make it portable (works now on windows too, belongs other OSes)
- ([20:28] <lsmith> Pierre: ok please commit)