Meson

This switches from autotools to meson. In the end, the conversion took me about a day of work. Thus it is a prety efficient build system if I compare it with autotools (I invested days and months to get where we are right now).

The advantage of meson:

• pretty much everything is way easier
• configuration is defined in the same file and thus in the same location as compilation which makes it much more direct
• adds the ability to easily pull in other projects to be built instead of need to install all dependencies to system
• pkg-config files are generated and thus kind of no longer our thing to deal with (such as that it tracks dependencies from single location)
• Meson's documentation is simply awesome compared to a mess of autotools

Disadvantages:

• Valgrind support is not exactly nice so I had to implement our own way to run in valgrind
• Flawfinder is run on all files instead of just sources because I was unable to reasonably get all source files in project (cppcheck on the other hand works even better thanks to direct integration)
• The build has to be always in subdirectoru (out of tree) but that is probably just rather habit than an issue
• It is something new and whole team would have to learn it and all C projects would have to be ported to it