c++17: drop experimental::filesystem

Use the real filesystem library, and drop support for building with
experimental under c++14.

Signed-off-by: Jayanth Othayoth <ojayanth@in.ibm.com>
Change-Id: I730c0d6dce53b5e0aa0867cddb7f325cdb9b45fc
diff --git a/dump_serialize.cpp b/dump_serialize.cpp
index 799b142..89c74c8 100644
--- a/dump_serialize.cpp
+++ b/dump_serialize.cpp
@@ -14,18 +14,18 @@
 
 using namespace phosphor::logging;
 
-void serialize(const ElogList& list, const fs::path& dir)
+void serialize(const ElogList& list, const std::filesystem::path& dir)
 {
     std::ofstream os(dir.c_str(), std::ios::binary);
     cereal::BinaryOutputArchive oarchive(os);
     oarchive(list);
 }
 
-bool deserialize(const fs::path& path, ElogList& list)
+bool deserialize(const std::filesystem::path& path, ElogList& list)
 {
     try
     {
-        if (fs::exists(path))
+        if (std::filesystem::exists(path))
         {
             std::ifstream is(path.c_str(), std::ios::in | std::ios::binary);
             cereal::BinaryInputArchive iarchive(is);
@@ -37,7 +37,7 @@
     catch (cereal::Exception& e)
     {
         log<level::ERR>(e.what());
-        fs::remove(path);
+        std::filesystem::remove(path);
         return false;
     }
 }