dynCall using BigInt without requiring BigInt64Array?

I have been having some trouble recently with side modules using things like `invoke_jiji` when there is no `dyncall_jiji` emitted in the main module. Pyodide assumes that people have `BigInt` for certain purposes, but we are not currently assuming that `BigInt64Array` is present. Perhaps we should just set `-s WASM_BIGINT`, but I was wondering if there an intermediate option where we don't assume that `BigInt64Array` exists but we do dynamic calls using `BigInt`.

According to caniuse, 93% of browsers support some form of Wasm, 90.3% of browsers support `BigInt` but only 83.3% of browsers support `BigInt64Array` (Safari finally does since September, but more people use Safari 14 than Safari 15).