mipsevm: test sol trace util with MIPS.sol, remove Hello.sol

contracts/src/Hello.sol

-pragma solidity ^0.7.6;
-
-// Hello-world contract to test source maps and instrumentation
-contract Hello {
-
-    function helloWorld(uint32 x) public returns (uint32) {
-        require(x > 3, "test");
-        return x + 100;
-    }
-}

mipsevm/solutil_test.go

@@ -8,9 +8,9 @@ import (
 )
 
 func TestSourcemap(t *testing.T) {
-	contract, err := LoadContract("Hello")
+	contract, err := LoadContract("MIPS")
 	require.NoError(t, err)
-	srcMap, err := contract.SourceMap([]string{"../contracts/src/Hello.sol"})
+	srcMap, err := contract.SourceMap([]string{"../contracts/src/MIPS.sol"})
 	require.NoError(t, err)
 	for i := 0; i < len(contract.DeployedBytecode.Object); i++ {
 		fmt.Println(srcMap.FormattedInfo(uint64(i)) + ": test")