Don't use IFTODT macro.

Don't use IFTODT macro.

IFTODT is provided by libc to convert from mode_t (as included in e.g.
struct fstat) to d_type (unsigned char element of struct dirent, as
returned by e.g. readdir). However, fuse actually uses a different
struct fuse_dirent with a "type" field of type uint32.
In other words, the semantics of (struct fuse_dirent).type are
not necessarily the same as those of (struct dirent).d_type.