Fix for running the export templates with newer emscripten versions.

[Relintai]

The issue is pretty much that argv[0] gets set to ./this.program, with the newer emscripten versions, and parameters are only added after this into the argv array.
(@fidli was talking about this in #32117.)

This is a really simple, no-refactor fix. I'm not familiar enough with emscripten yet to be able to make a more roboust solution, but at the very least it shows where the actual problem is.

By the way I found emscripten-core/emscripten#2431.
This is exactly the same thing, maybe they reintroduced this?

I've tested this with both the 1.38.27, and master emsdk.

fixes #32117
fixes #32422

[akien-mga]

It would be good to figure out why this changed in Emscripten, and whether this was a conscious compatibility breakage or if it's an upstream bug.

[Relintai]

I got lucky, this causes the issue:

emscripten-core/emscripten@ea85994

if I use new emscripten versions, in the wrapper js file the generated program name setup code looks like this: var thisProgram="./this.program"
On older versions it looks like this: Module["thisProgram"]="./this.program"

By the way changing var thisProgram="./this.program" to the proper expected string, makes everything work again.

I'll update the pr when I figure out how this should be used.

Close, but the real reason is that the runtime environment loses the ["thisProgram"] key. Not yet sure why.

Edit:

I think it's probably something to do with promises not fullfilling quick enough, because if I console.log the Module variable in the generated .js's RuntimeEnvironment, the thisProgram member is there, but if I try to access it it just says undefined.

But I think it will be cleaner to just separate the appname <-> .pck name guessing code, and just use 2 constants in the main html file. I'll build this, and force push it when done. (If it's good enough.)

[akien-mga]

Thanks!

[akien-mga]

Cherry-picked for 3.1.2.