Indirect call signature mismatch with MAIN_MODULE=1

[jeromelaban]

I'm opening a different bug, even if it was related to #9810 and mentioned in #9562.

The following code does not run properly using 1.39.3:

#include <stdio.h>

long long testAdd(int a, int b)
{
    return a+b;
}

typedef long long (*testAddHandler)(int, int);

int main()
{
    testAddHandler h = &testAdd;
    long long r = h(42, 42);

    printf("Result: %d\n", r);
}

Built with emcc myfile.cpp -s MAIN_MODULE=1.

And fails with the following:

exception thrown: RuntimeError: indirect call signature mismatch,@http://localhost:8000/index.wasm:wasm-function[176]:0x8988
@http://localhost:8000/index.wasm:wasm-function[177]:0x89d4
Module._main@http://localhost:8000/index.js:41584:32
callMain@http://localhost:8000/index.js:52555:15
doRun@http://localhost:8000/index.js:52614:23
run/<@http://localhost:8000/index.js:52625:7

[kripken]

Thanks @jeromelaban !

When I wrote #9810 I simplified that testcase, and it turns out I
simplified it so much it missed a second bug that existed...

Fix in #9855