Fixing package requirements.

According to https://travis-ci.org/sagotch/ollvm-travis-ci/builds/36844794,
this repository state *may* be the good one for package distribution.

`aclocal` and `automake` should not be requirements, so I added `aclocal.m4` file and used `AM_MAINTAINER_MODE([enable])` in `configure.ac`.

Could someone review these changes?

See #5