[mlir][sparse] Fix windows build.

[bixia]

Rebase.

mlir/lib/Dialect/SparseTensor/Transforms/SparseTensorRewriting.cpp

LogicalResult sparse2SparseRewrite(ConvertOp op,
     // Sort the COO tensor so that its elements are ordered via increasing
     // indices for the storage ordering of the dst tensor.
     auto dynShape = {ShapedType::kDynamicSize};
     auto indTp =
         MemRefType::get(dynShape, getIndexOverheadType(rewriter, encSrc));
     uint64_t rank = dstTp.getRank();
     // Gather the indices-arrays in the dst tensor storage order.
     SmallVector<Value, 4> xs(rank, Value());
-    for (int64_t i = 0; i < rank; i++) {
+    for (uint64_t i = 0; i < rank; i++) {
       uint64_t orgDim = toOrigDim(encSrc, i);
       xs[toStoredDim(encDst, orgDim)] = rewriter.create<ToIndicesOp>(
           loc, indTp, src, rewriter.getIndexAttr(orgDim));
     }
 
     // Retrieve NNZ.
     auto ptrTp =
         MemRefType::get(dynShape, getPointerOverheadType(rewriter, encSrc));