Recommend pkg-config when systemd fails
We used to show an error like this when configure failed to find systemd:
configure: error: Package requirements (systemd >= 209) were not met: No package 'systemd' found Consider adjusting the PKG_CONFIG_PATH environment variable if you installed software in a non-standard prefix. Alternatively, you may set the environment variables SYSTEMD209_CFLAGS and SYSTEMD209_LIBS to avoid the need to call pkg-config. See the pkg-config man page for more details.
But now we don't:
checking for pkg-config... no checking for SYSTEMD... no configure: Okay, checking for systemd a different way... checking for SYSTEMD... no configure: error: Explicitly requested systemd support, but systemd not found
This issue also affects lzma, and any other package that requires pkg-config.
In fact, lzma silently fails:
./configure --enable-lzma silently fails if pkg-config is not installed: https://gitlab.com/eighthave/tor/pipelines/85811623