Enable discovery multicast for unit tests

tools/travis/travis_osx_script.sh

@@ -47,7 +47,7 @@ else
 
     echo "Debug build and unit tests with valgrind" && echo -en 'travis_fold:start:script.build.unit_test\\r'
     mkdir -p build && cd build
-    cmake -DCMAKE_BUILD_TYPE=Debug -DUA_BUILD_EXAMPLES=ON -DUA_BUILD_UNIT_TESTS=ON -DUA_ENABLE_COVERAGE=OFF -DUA_ENABLE_VALGRIND_UNIT_TESTS=OFF ..
+    cmake -DCMAKE_BUILD_TYPE=Debug -DUA_BUILD_EXAMPLES=ON -DUA_ENABLE_DISCOVERY=ON -DUA_ENABLE_DISCOVERY_MULTICAST=ON -DUA_BUILD_UNIT_TESTS=ON -DUA_ENABLE_COVERAGE=OFF -DUA_ENABLE_VALGRIND_UNIT_TESTS=OFF ..
     make -j && make test ARGS="-V"
     cd .. && rm -rf build
 	echo -en 'travis_fold:end:script.build.unit_test\\r'