Don't pass --user to mysqld if --user is not used


netware/Makefile.am:
  Make it possible to use mysys functions in mysql_test_run.c
netware/mysql_test_run.c:
  Make it possible to use mysys functions in mysql_test_run.c
scripts/mysql_install_db.sh:
  Don't pass --user to mysqld if --user is not used