[util] Remove umask manipulation from makedirs
    
    This causes a race condition: umask is process-wide setting, so any file
    created by another thread while the umask is set to 0 will have wrong
    permissions. This also removes the possible problem of not resetting the
    umask if exception is raised.
    
    Fixes: #239
    Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>