Avoid unnecessary temporary value when coercing a record that's alrea…

…dy the right type.

The combination of this commit with the previous one now lets the
examples in #425 all execute with the same performance.

Closes #425.

src/Expr.cc

@@ -3758,6 +3758,9 @@ ValPtr RecordCoerceExpr::InitVal(const zeek::Type* t, ValPtr aggr) const
 
 ValPtr RecordCoerceExpr::Fold(Val* v) const
 	{
+	if ( same_type(GetType(), Op()->GetType()) )
+		return IntrusivePtr{NewRef{}, v};
+
 	auto val = make_intrusive<RecordVal>(GetType<RecordType>());
 	RecordType* val_type = val->GetType()->AsRecordType();