RFC: meson: add mesonbuild support

[pabigot]

I recognize there's enough complexity trying to maintain both CMake and Makefile, but meson has a few benefits including trivial support for Google Test and doxygen, and better provision of dependencies in pkgconfig than CMake.

Using AMQP-CPP as a subproject in a meson-based application becomes a simple matter of dropping something like the following as subprojects/amqpcpp.wrap:

[wrap-git]
directory = amqpcpp
url = /mnt/devel/external/RabbitMQ/AMQP-CPP
revision = dd00810f7fa3cc88470c52b274ea65c333cb5d66

and adding this to the project meson.build:

amqp_dep = dependency('amqpcpp',
                      default_options: [
                        'linux-tcp=true',
                      ],
                      fallback: ['amqpcpp', 'amqpcpp_dep'])

I've only tested this on Linux and with linux-tcp set.

If this is something that could be merged, I'd be happy to add some documentation. The primary value to this project of merging it is Google Test support; secondarily it might help with #208. If it's not wanted I'll maintain it myself or submit it to wrapdb.

[EmielBruijntjes]

I'm happy to merge this if that helps you, but the problem that I have with these kind of PR's is is that I do not use this technology, and I am also not familiar with it. I can therefore not maintain it or can judge what the quality of it is.

So I wait a little while to see if there are others who think this is helpful too before I press the merge-button.

[pabigot]

It also adds a step for @RafalGoslawski as the version number needs to be updated in meson.build when a release is tagged.

I agree this should depend on interest from the rest of the user community.