[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/gpu/shared_memory.cc

@@ -482,7 +482,7 @@ void SharedMemory::TryFindUploadRange(const uint32_t& block_first,
 }
 
 static bool UploadRange_DoBestScanForward(uint64_t v, uint32_t* out) {
-#if XE_ARCH_AMD64 == 1
+#if XE_ARCH_AMD64 == 1 && XE_PLATFORM_WIN32
   if (!v) {
     return false;
   }