src: Reorganizing source code in preparation to merge NRD code

Note that as of this commit, there are several changes in location of
compiled binaries in `build/` folder:

* `nfd` has been moved to `build/bin/nfd`
* `unit-tests` has been split into `unit-tests-core` and `unit-tests-daemon`

Change-Id: I2c830c117879edbaa5457d6423c13f0273285919
Refs: #1486
diff --git a/tests/test-common.hpp b/tests/test-common.hpp
index 2e555b4..f4fc0ed 100644
--- a/tests/test-common.hpp
+++ b/tests/test-common.hpp
@@ -22,8 +22,8 @@
  * NFD, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
  **/
 
-#ifndef NFD_TEST_COMMON_HPP
-#define NFD_TEST_COMMON_HPP
+#ifndef NFD_TESTS_TEST_COMMON_HPP
+#define NFD_TESTS_TEST_COMMON_HPP
 
 #include <boost/test/unit_test.hpp>
 #include "core/global-io.hpp"
@@ -79,4 +79,4 @@
 } // namespace tests
 } // namespace nfd
 
-#endif // NFD_TEST_COMMON_HPP
+#endif // NFD_TESTS_TEST_COMMON_HPP