Meson only runs required targets. The key_encrypted_pem and
cert_encrypted_pem targets added in 020b0db090dc8e197cbedbdc4db7e3120eda5333
and 8191fd8e6c5a27e034a34084afe61f17a9420cfa weren't added to the list
of targets required by the test target, so the generation of the
encrypted certs was skipped, resulting in the failure of
BindServerTest.BindAndListenSeparatelySSLEncryptedKey.
* meson: fix regression that broke extracting version
In commit 33f67386fec8040a36a26b2038b39dd8dcf2814d the code that
heuristically parsed the version broke due to the version being moved
around into a more easily accessible define.
While we are at it, pass the exact path of httplib.h to un-break usage
as a meson subproject. This was broken in commit
8ecdb1197967dea050fd38a8e9b5020e02320b31 which checked the return code
of trying to get the version; it was always broken, but formerly failed
in silence and resulted in no version number.
* meson: use the compiler builtins to extract the version from the header
As a convenient string define, it is now possible to ask the
preprocessor what the version of cpp-httplib is. This can be used from
meson too, in order to avoid encoding C++ file structure into python
regexes.
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 change is based on RFC7230, § 3.5 'Message Parsing Robustness': "Although the line terminator for the start-line and header fields is the sequence CRLF, a recipient MAY recognize a single LF as a line terminator and ignore any preceding CR."
