[All] Fixed multiple issues during build on Linux

- Added some fixes introduced by RodoMa92 in PR198

- Lack of AVX2 extension (should be done differently in the future)
- Disable deprecated-volatile warning
- Added missing override in posix EventInfo, ImGui notification class and XContent class
- Removed not used XAudio2.h include in XMP
- Fixed missing switch-case in XObject
- Added fugly template in native_list.h
- Fixed multiple smaller issues

src/xenia/kernel/xsocket.cc

@@ -74,9 +74,10 @@ X_STATUS XSocket::Close() {
 }
 
 X_STATUS XSocket::GetOption(uint32_t level, uint32_t optname, void* optval_ptr,
-                            int* optlen) {
+                            uint32_t* optlen) {
   int ret =
-      getsockopt(native_handle_, level, optname, (char*)optval_ptr, optlen);
+      getsockopt(native_handle_, level, optname, static_cast<char*>(optval_ptr),
+                 reinterpret_cast<socklen_t*>(optlen));
   if (ret < 0) {
     // TODO: WSAGetLastError()
     return X_STATUS_UNSUCCESSFUL;