Fix bug 14758 - "smbd async dosmode = yes" returns FILE_ATTRIBUTE_NORMAL for all entries in a directory
Passes ci. This is a regression from 4.14. Adds a regression test to ensure this doesn't happen again. Also fixes our test environment so we actually test our async dos mode code, and ensures we use handle-based calls in the vfs_default code.
Let's get this into 4.15.rc1 !