examples: Fix directory determining logic
examples: Fix directory determining logic

On libarchive 3.0.1 to 3.0.3, archive_entry_filetype() returns AE_IFREG
for all members of a zip file read from a seekable stream. Look for a
trailing slash to ensure that directories are not falsely evaluated as
regular files.

cmusatyalab/diamond-core-filters,cmusatyalab/diamond-core-filters,cmusatyalab/diamond-core-filters