Problem was that link file (.isl) is also opened using O_DIRECT
    mode and if this fails the whole create table fails on internal
    error.

    Fixed by not using O_DIRECT on link files as they are used only
    on create table and startup and do not contain real data.
    O_DIRECT failures are successfully ignored for data files
    if O_DIRECT is not supported by file system on used
    data directory.