core: drop std::function and ndn::Exclude from common.hpp, add ndn::optional

Change-Id: Ie3983d8b6f9929430efd8ada8d942e3f95755cd4
diff --git a/tests/daemon/mgmt/fib-manager.t.cpp b/tests/daemon/mgmt/fib-manager.t.cpp
index 428b15b..e2986bc 100644
--- a/tests/daemon/mgmt/fib-manager.t.cpp
+++ b/tests/daemon/mgmt/fib-manager.t.cpp
@@ -35,8 +35,6 @@
 namespace nfd {
 namespace tests {
 
-using ndn::nullopt;
-
 class FibManagerFixture : public NfdManagerCommonFixture
 {
 public:
@@ -98,9 +96,9 @@
    */
   CheckNextHopResult
   checkNextHop(const Name& prefix,
-               ndn::optional<size_t> expectedNNextHops = nullopt,
-               ndn::optional<FaceId> faceId = nullopt,
-               ndn::optional<uint64_t> expectedCost = nullopt) const
+               optional<size_t> expectedNNextHops = nullopt,
+               optional<FaceId> faceId = nullopt,
+               optional<uint64_t> expectedCost = nullopt) const
   {
     const fib::Entry* entry = m_fib.findExactMatch(prefix);
     if (entry == nullptr) {