enabling `-gsource-map` disables JS whitespace minification

[jmcclellan-figma]

Due to logic here, it seems like linking with -gsource-map will automatically disable whitespace minification for the js file - this was a bit surprising to me because I wanted source maps for my wasm file while still having whitespace removed from my js file.

[kripken]

Yes, I think atm -gsource-map enables some amount of "debug" stuff. See #20462 for some thoughts about changing that.

[adamvleggett]

@kripken -gsource-map enabling -g automatically and not being able to then override it with -g0 makes it impossible to generate a fully minified .wasm artifact and still get a source map. This seems like a common use case and may make it impossible for some projects to use recent versions of Emscripten.

This was possible to do in Emscripten 3.1.45 (seemingly contrary to #20462), which I last tested with.

It's possible to do in Emscripten 4.0.12 by patching cmdline.py or settings_internal.js to set GENERATE_SOURCE_MAP=1 but only by doing that.

[kripken]

@adamvleggett Interesting that this worked before - I'm not sure why, offhand, perhaps it was a quirk/bug?

I opened #24936 now with an option to allow this. Let's see what people think.