A pkg-config file was previously installed only if cpp-httplib was being
built as a compiled library.
Since architecture-independent .pc files
can exist in /usr/share/pkgconfig, it can be useful to install one even
when installing the header-only version (for example, it could be used
by third party projects to easily find out if cpp-httplib is installed
and its version, using something like Meson's `dependency()` or CMake's
`pkg_check_modules()`).
The change makes the Meson build behave a bit more like the CMake one,
as it also always installs a CMake Config file, but here the pkg-config
file gets installed to the correct architecture-independent directory
(`datadir` represents /usr/share on Linux and simiar systems).
Lastly, I made some minor cleanups.
This integrates the "main" test suite (test/test.cc) in Meson.
This allows to run the tests in the CI with the Meson-built version of
the library to ensure that nothing breaks unexpectedly.
It also simplifies life of downstream packagers, that do not have to
write a custom build script to split the library and run tests but can
instead just let Meson do that for them.
* Full Meson support
cpp-httplib can be now built with Meson even in compiled library mode.
The library is built with LTO, supports OpenSSL, zlib and Brotli,
and the build system also generates a pkg-config file when needed.
Compared to the CMake file this one is quite small (more than five times
smaller!), and maintaining it won't be an issue :)
* meson: automatic versioning
* Add header-only Meson support
This allows users to call `dependency('httplib')` and have the include
directory automatically configured
* Rename `httplib` to `cpp-httplib`
