Some filesystems violate against the POSIX rules.

when backing up a filesystem mounted to a linux host via ntfs, we get an
assertion error:

backup-sd-fd: bfile.c:1031-0 open file
/bacula-mounts/INEZ/part2/Users/<username>/AppData/Local/Packages/WinStore_cw5n1h2txyewy/AC/Microsoft/Windows
Store/Cache/0/0-Featured-https∺∯∯next-services.apps.microsoft.com∯browse∯6.2.9200-1∯667∯c∯DE∯Featured∯10895826.dat
backup-sd-fd: backup.c:983-0 Send data to SD len=6552
backup-sd-fd: find_one.c:756-0 Failed ASSERT: name_max+1 >
(int)sizeof(struct dirent) + (int)NAMELEN(entry)

Fixes 250: bareos-fd asserts when reading a file from ntfs volume mounted on linux