Remove needless AM_INIT_AUTOMAKE arguments

    configure.ac:19: warning: AM_INIT_AUTOMAKE: two- and three-arguments forms are deprecated.  For more info, see:
    configure.ac:19: http://www.gnu.org/software/automake/manual/automake.html#Modernize-AM_005fINIT_005fAUTOMAKE-invocation