Changing to build type DEBUG

Former-commit-id: 5ffdbf89099bace2c8521442ea27dda2c75442a9

.travis.yml

@@ -11,7 +11,7 @@ matrix:
         - cd python
         - mkdir build
         - cd build
-        - cmake -DCMAKE_CXX_COMPILER=g++-4.8 -DCMAKE_C_COMPILER=gcc-4.8 ../
+        - cmake -DCMAKE_CXX_COMPILER=g++-4.8 -DCMAKE_C_COMPILER=gcc-4.8 -DCMAKE_BUILD_TYPE=Debug ../
         - make -j 2
         - cd ../../
         - cd tutorial

python/CMakeLists.txt

@@ -30,7 +30,7 @@ if (UNIX)
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -fPIC")
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fPIC")
   if (NOT ${U_CMAKE_BUILD_TYPE} MATCHES DEBUG)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fvisibility=hidden")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fvisibility=hidden -flto")
   endif()
 endif()