#4 Resolve autoconf warnings

[Yegor Yefremov]

This patch resolves following warning:

configure.in:10: warning: AM_INIT_AUTOMAKE: two- and three-arguments forms are deprecated. For more info, see:
configure.in:10: http://www.gnu.org/software/automake/manual/automake.html#Modernize-AM_005fINIT_005fAUTOMAKE-invocation