Convert config file format from python to something simpler.

[sbc100]

See #26453 for a plan for create some kind of native entry point for emcc, that can avoid running python except for linking.

There should really be no need to run the full python interpreter just for the compiler config file. I suggest we transition to something simple. Perhaps a simple key, value text file, json.

Step 1 in doing this is probably to separate the testing config, which is slightly more complex from the core compiler config, which is really just a few paths.

[brendandahl]

There's also already clang config files. They are just plain text though and turn into command line flags.

[sbc100]

Do you think it makes sense for our config file to look like just command line args though?

As opposes to current format which looks like:

NODE_JS = '.../node/22.16.0_64bit/bin/node'
LLVM_ROOT = '/upstream/bin'
BINARYEN_ROOT =  '/upstream'
EMSCRIPTEN_ROOT =  '/upstream/emscripten'

Are you suggesting we add command like flags for all of these and then use a config file that looks like this:

--node-path=node/22.16.0_64bit/bin/node --llvm-path=upstream/bin --binaryen-path=upstream

?

[sbc100]

maybe not so bad if we put each on its own line:

--node-path=node/22.16.0_64bit/bin/node
--llvm-path=upstream/bin
--binaryen-path=upstream

[sbc100]

Ooo, they even support a magic <CFGDIR> which is very useful to emsdk

[brendandahl]

Are you suggesting we add command like flags for all of these and then use a config file that looks like this:

--node-path=node/22.16.0_64bit/bin/node --llvm-path=upstream/bin --binaryen-path=upstream

?

I was thinking more the add command line flags option, to be more like clang. I don't have a much of an opinion here, more just pointing out some prior art.