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

And fix the resulting compilation errors.

Change-Id: I2f8a8406542d297bfeeb4c922812ff1879a4dff6
Refs: #4248
diff --git a/tests/tools/nfdc/status-fixture.hpp b/tests/tools/nfdc/status-fixture.hpp
index b955f7a..8c9eb3c 100644
--- a/tests/tools/nfdc/status-fixture.hpp
+++ b/tests/tools/nfdc/status-fixture.hpp
@@ -48,7 +48,7 @@
   operator()(Face&, KeyChain&) const
   {
     return make_unique<ValidatorNull>();
-  };
+  }
 };
 
 /** \brief fixture to test status fetching routines in a \p Module