remove std::experimental usage

All of the std::experimental usages in this repository have a well
supported counterpart in std as of C++17.  Switch to use them.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I4cdf5cd27053ce85c7f70c215ee9456f96f79f42
diff --git a/src/count.hpp b/src/count.hpp
index f231f26..35bf5ed 100644
--- a/src/count.hpp
+++ b/src/count.hpp
@@ -65,12 +65,12 @@
                 // and save the op result in storage[1].
                 const auto& storage = std::get<storageIndex>(item.second);
                 // Don't count properties that don't exist.
-                if (std::get<valueIndex>(storage.get()).empty())
+                if (!std::get<valueIndex>(storage.get()).has_value())
                 {
                     return false;
                 }
                 const auto& value =
-                    any_ns::any_cast<T>(std::get<valueIndex>(storage.get()));
+                    std::any_cast<T>(std::get<valueIndex>(storage.get()));
                 auto r = propertyOp(value);
 
                 std::get<resultIndex>(storage.get()) = r;