For llvm8-dev llvm-config executable is no longer in PATH (it is in PATH now for llvm9-dev) and now it is in /usr/lib/llvm8/bin/llvm-config, so it is more reliable to adjust $PATH before calling meson build. It will work for all past, current and future llvm versions. Fixes 90d3deb7b4f5f1801f09251b981f84adc7b5817e [ci:skip-build]: already built successfully in CI