Add -Wextra-semi -Wundefined-func-template to the default CXXFLAGS

And fix the resulting compilation errors.

Change-Id: I16f679836a0cf2a3ff5dfcf6f6b67bfbfe4cdbd7
Refs: #4248
diff --git a/src/mgmt/nfd/channel-status.cpp b/src/mgmt/nfd/channel-status.cpp
index e6e53f4..5fd93b1 100644
--- a/src/mgmt/nfd/channel-status.cpp
+++ b/src/mgmt/nfd/channel-status.cpp
@@ -47,11 +47,7 @@
   return totalLength;
 }
 
-template size_t
-ChannelStatus::wireEncode<encoding::EncoderTag>(EncodingImpl<encoding::EncoderTag>&) const;
-
-template size_t
-ChannelStatus::wireEncode<encoding::EstimatorTag>(EncodingImpl<encoding::EstimatorTag>&) const;
+NDN_CXX_DEFINE_WIRE_ENCODE_INSTANTIATIONS(ChannelStatus);
 
 const Block&
 ChannelStatus::wireEncode() const