Disallow structs in events without ABIEncoderV2

test/libsolidity/syntaxTests/emit/emit_empty.sol

@@ -0,0 +1,7 @@
+contract C {
+  function f() public {
+    emit;
+  }
+}
+// ----
+// ParserError: (45-46): Expected event name or path.

test/libsolidity/syntaxTests/emit/emit_non_event.sol

@@ -0,0 +1,10 @@
+contract C {
+  uint256 Test;
+
+  function f() public {
+    emit Test();
+  }
+}
+// ----
+// TypeError: (63-69): Type is not callable
+// TypeError: (63-67): Expression has to be an event invocation.