Fix getExternalBalance

[loredanacirstea]

Fix

ewasm-jsvm/tests/jsvm.test.js

Lines 246 to 252 in 3b9ca9d

	it('test c6 getExternalBalance', async function () {
	const ewmodule = ewasmjsvm.initialize(contracts.c6.bin, c6Abi);
	const runtime = await ewmodule.main(DEFAULT_TX_INFO);
	deployments.c6 = runtime;
	const answ = await runtime.main(accounts[0].address, DEFAULT_TX_INFO);
	// expect(answ.balance).toBe(accounts[0].balance);
	});

getExternalBalance correctly stores the balance in memory:

ewasm-jsvm/src/index.js

Lines 205 to 208 in 3b9ca9d

	balance.set(tightValue, size - tightValue.length);
	storeMemory(balance, resultOffset_i32ptr, size);
	console.log('getExternalBalance', logu8a(loadMemory(resultOffset_i32ptr, size)));

However, it never gets written to the proper return pointer. So it is always 0 when returned:

ewasm-jsvm/tests/contracts/c6.yul

Lines 14 to 18 in 3b9ca9d

	// getExternalBalance i32
	let account := mload(_calldata)
	mstore(_data, balance(account))
	return (_data, 32)