tests: Conditional compilation of tests (including boost-based unit tests)

To compile tests, code needs to be configured with --with-tests option,
otherwise all tests are disabled.

Tests that are based on Boost's unit test framework are enabled only if
the framework is detected during the configure time.

Change-Id: Ia1768e24b088e4f19d2a8799c6d5baeabb2f44c5
diff --git a/tests_boost/test-encode-decode-data.cpp b/tests_boost/test-encode-decode-data.cpp
index a89011b..198fe71 100644
--- a/tests_boost/test-encode-decode-data.cpp
+++ b/tests_boost/test-encode-decode-data.cpp
@@ -11,6 +11,12 @@
 
 #include <fstream>
 
+#if __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wtautological-compare"
+#endif
+
+
 #include <cryptopp/rsa.h>
 #include <cryptopp/osrng.h>
 #include <cryptopp/files.h>
@@ -187,8 +193,6 @@
 
   Block dataBlock;
   BOOST_REQUIRE_NO_THROW(dataBlock = d.wireEncode());
-  ofstream of("data.tlv");
-  of.write((const char*)dataBlock.wire(), dataBlock.size());
 
   BOOST_REQUIRE_EQUAL_COLLECTIONS(Data1, Data1+sizeof(Data1),
                                dataBlock.begin(), dataBlock.end());