Function operator delete

extern/imgui/imgui.h:1814–1814

struct ImNewWrapper {};
inline void* operator new(size_t, ImNewWrapper, void* ptr) { return ptr; }
inline void  operator delete(void*, ImNewWrapper, void*)   {} // This is only required so we can use the symmetrical new()
#define IM_ALLOC(_SIZE)                     ImGui::MemAlloc(_SIZE)
#define IM_FREE(_PTR)                       ImGui::MemFree(_PTR)
#define IM_PLACEMENT_NEW(_PTR)              new(ImNewWrapper(), _PTR)