Enable memoverride in variant.h (#266)

public/variant.h

@@ -17,6 +17,8 @@
 #include "tier1/utlscratchmemory.h"
 #include "resourcefile/resourcetype.h"
 
+#include "tier0/memdbgon.h"
+
 FORWARD_DECLARE_HANDLE( HSCRIPT );
 
 // ========
@@ -975,4 +977,6 @@ typedef CVariantBase<CEntityVariantAllocator> CEntityVariant;
 
 typedef CVariant variant_t;
 
+#include "tier0/memdbgoff.h"
+
 #endif // CVARIANT_H