obtaining socket fd throws `Invalid Socket Handle`

```
inValue.mPtr = 0x0
```

```haxe
var socket = new sys.net.Socket();
fd(socket.__s);
```
```haxe
@:native("SOCKET_FD")
extern public static function fd(socket: Socket): Int;
```
```haxe
@:headerCode("
int SOCKET_FD(Dynamic socket);
")

@:cppFileCode("
#include
#include

#define APPNAME \"MyApp\"

typedef int SOCKET;

static int socketType = 0;

struct SocketWrapper : public hx::Object
{
HX_IS_INSTANCE_OF enum { _hx_ClassId = hx::clsIdSocket };

SOCKET socket;

int __GetType() const { return socketType; }
};

SOCKET val_sock(Dynamic inValue)
{
__android_log_print(ANDROID_LOG_VERBOSE, APPNAME, \"inValue.mPtr = %p\", inValue.mPtr);
if (inValue.mPtr)
{
int type = inValue->__GetType();
if (type==vtClass)
{
__android_log_print(ANDROID_LOG_VERBOSE, APPNAME, \"type is vtClass\");
inValue = inValue->__Field( HX_CSTRING(\"__s\"), hx::paccNever );
__android_log_print(ANDROID_LOG_VERBOSE, APPNAME, \"inValue.mPtr = %p\", inValue.mPtr);
if (inValue.mPtr==0)
return 0;
type = inValue->__GetType();
}

__android_log_print(ANDROID_LOG_VERBOSE, APPNAME, \"type = %d\", type);
__android_log_print(ANDROID_LOG_VERBOSE, APPNAME, \"socketType = %d\", socketType);
if (type==socketType)
return static_cast(inValue.mPtr)->socket;
}

hx::Throw(HX_CSTRING(\"Invalid socket handle\"));
return 0;
}

int SOCKET_FD(Dynamic socket) {
return val_sock(socket);
}
```