Include missing header files.
    
    Function get_krb5_tgt is declared in header file krb5_helper.h, but this header
    file was not included in implementation file krb5_helper.c
    
    Function fs_dirs_create is declared in header file fs.h, but this header file
    was not included in the implementation file fs.c
    
    Signed-off-by: Lukas Slebodnik <lslebodn@redhat.com>
    Reviewed-By: Petr Spacek <pspacek@redhat.com>