autotools

[linkdd]

Using autotools to build neb2amqp would be great.

It would allow for example :

$ ./configure --with-nagios3
$ make

or

$ ./configure --with-nagios4
$ make

[ziirish]

Not sure it is mandatory.

We don't rely on any external dependency as we embed them within our source tree.
The benefit is then very limited.

Right now I have added a new target to generate either the 3.x compatible module or 4.x one.
We could imagine a default target that generates both modules.

We can rethink about it when 4.x branch is well tested.