[mlir][sparse] Correcting the use of emplace_back

[wrengr]

Summary

The emplace commands are variadic and should take all the constructor arguments directly, since they implicitly call the constructor themselves in order to avoid the cost of constructing and then moving/copying temporaries.

mlir/lib/ExecutionEngine/SparseUtils.cpp

SparseTensor(const std::vector<uint64_t> &szs, uint64_t capacity)
     if (capacity)
       elements.reserve(capacity);
   }
   /// Adds element as indices and value.
   void add(const std::vector<uint64_t> &ind, V val) {
     assert(getRank() == ind.size());
     for (uint64_t r = 0, rank = getRank(); r < rank; r++)
       assert(ind[r] < sizes[r]); // within bounds
-    elements.emplace_back(Element<V>(ind, val));
+    elements.emplace_back(ind, val);
   }
   /// Sorts elements lexicographically by index.
   void sort() { std::sort(elements.begin(), elements.end(), lexOrder); }
   /// Primitive one-time iteration.
   const Element<V> &next() { return elements[pos++]; }
   /// Returns rank.
   uint64_t getRank() const { return sizes.size(); }
   /// Getter for sizes array.