[XAM] Cut handle mask from socket handles, added support for: NetDll_getsockopt

Only positive values should be interpreted as valid sockets!

src/xenia/kernel/xsocket.h

@@ -107,6 +107,8 @@ class XSocket : public XObject {
   X_STATUS Initialize(AddressFamily af, Type type, Protocol proto);
   X_STATUS Close();
 
+  X_STATUS GetOption(uint32_t level, uint32_t optname, void* optval_ptr,
+                     int* optlen);
   X_STATUS SetOption(uint32_t level, uint32_t optname, void* optval_ptr,
                      uint32_t optlen);
   X_STATUS IOControl(uint32_t cmd, uint8_t* arg_ptr);