tools/tests: fix compilation errors caused by bind and placeholders

refs #2175

Change-Id: I65eadb0d0ccf468c3d478236335dbf09aa4dcc71
diff --git a/tools/ndn-tlv-peek.cpp b/tools/ndn-tlv-peek.cpp
index dca57e0..5460096 100644
--- a/tools/ndn-tlv-peek.cpp
+++ b/tools/ndn-tlv-peek.cpp
@@ -33,9 +33,6 @@
 
 namespace ndntlvpeek {
 
-using ndn::_1;
-using ndn::_2;
-
 class NdnTlvPeek : boost::noncopyable
 {
 public:
diff --git a/tools/ndn-tlv-poke.cpp b/tools/ndn-tlv-poke.cpp
index 31ec561..45db702 100644
--- a/tools/ndn-tlv-poke.cpp
+++ b/tools/ndn-tlv-poke.cpp
@@ -34,9 +34,6 @@
 
 namespace ndntlvpoke {
 
-using ndn::_1;
-using ndn::_2;
-
 class NdnTlvPoke : boost::noncopyable
 {
 public:
diff --git a/tools/nfdc.cpp b/tools/nfdc.cpp
index bfae684..2ecba4d 100644
--- a/tools/nfdc.cpp
+++ b/tools/nfdc.cpp
@@ -70,9 +70,7 @@
 
 namespace nfdc {
 
-using ndn::bind;
-using ndn::_1;
-using ndn::_2;
+using std::bind;
 
 const ndn::time::milliseconds Nfdc::DEFAULT_EXPIRATION_PERIOD = ndn::time::milliseconds::max();
 const uint64_t Nfdc::DEFAULT_COST = 0;