Fix incorrect index

closes https://github.com/assimp/assimp/issues/3364

code/Common/StandardShapes.cpp

@@ -139,7 +139,7 @@ aiMesh *StandardShapes::MakeMesh(const std::vector<aiVector3D> &positions,
         aiFace &f = out->mFaces[i];
         f.mNumIndices = numIndices;
         f.mIndices = new unsigned int[numIndices];
-        for (unsigned int j = 0; i < numIndices; ++i, ++a) {
+        for (unsigned int j = 0; j < numIndices; ++j, ++a) {
             f.mIndices[j] = a;
         }
     }