AssbinExporter: Add assertion to silence a static analyzer warning

code/AssbinExporter.cpp

@@ -171,6 +171,7 @@ inline size_t Write<aiQuaternion>(IOStream * stream, const aiQuaternion& v)
     t += Write<float>(stream,v.x);
     t += Write<float>(stream,v.y);
     t += Write<float>(stream,v.z);
+    ai_assert(t == 16);
     return 16;
 }