Fix remapping for union field names

[reflectronic]

For code like:

union MyUnion
{
    struct { int a; };
};
void MyFunction()
{
    MyUnion myUnion;  
    myUnion.a = 10;
}

myUnion.a = 10; was translated to C# using the mangled name, not the actual name of the field in C# (Anonymous).