Fix build for AppleClang 11 (dmlc#9684)

Author: hcho3

src/common/ref_resource_view.h

@@ -76,7 +76,7 @@ class RefResourceView {
 
   [[nodiscard]] size_type size() const { return size_; }  // NOLINT
   [[nodiscard]] size_type size_bytes() const {            // NOLINT
-    return Span{data(), size()}.size_bytes();
+    return Span<const value_type>{data(), size()}.size_bytes();
   }
   [[nodiscard]] value_type* data() { return ptr_; };              // NOLINT
   [[nodiscard]] value_type const* data() const { return ptr_; };  // NOLINT

tests/cpp/common/test_io.cc

@@ -148,7 +148,8 @@ TEST(IO, Resource) {
     fout << 1.0 << std::endl;
     fout.close();
 
-    auto resource = std::make_shared<MmapResource>(path, 0, sizeof(double));
+    auto resource = std::shared_ptr<MmapResource>{
+      new MmapResource{path, 0, sizeof(double)}};
     ASSERT_EQ(resource->Size(), sizeof(double));
     ASSERT_EQ(resource->Type(), ResourceHandler::kMmap);
     ASSERT_EQ(resource->DataAs<double>()[0], val);