If ragel 6.10 is not found, build it from source.
Seems to work, except that ragel uses exceptions and we configure
HarfBuzz build to not use exceptions, and I can’t find away to enable
exceptions only for the ragel subproject. I had to remove cpp_eh=none
from default options and try to disable exceptions in MSVC manually
(other compilers are already handled).
This way it won't ruin incremental builds.
We need a better way to declare source altering tasks
https://github.com/mesonbuild/meson/issues/7156
yet this is good enough despite being not idiomatic.
It is however not that smooth yet as the change may is detected on the
next meson run. One of course can issue ./gen-ragel-artifacts.py
manually for better experience before running meson.
Khaled Hosny
Behdad Esfahbod
David Corbett
Ebrahim Byagowi