Fix for ports-gcc, the code generates warnings that triggers a
build failure

Index: CMakeLists.txt
--- CMakeLists.txt.orig
+++ CMakeLists.txt
@@ -5,7 +5,7 @@ cmake_minimum_required(VERSION 2.8)
 find_package(PythonInterp REQUIRED)
 
 if(CMAKE_COMPILER_IS_GNUCXX OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
-    set(CMAKE_CXX_FLAGS "-Wall -Wextra -Werror ${CMAKE_CXX_FLAGS}")
+    set(CMAKE_CXX_FLAGS "-Wall -Wextra ${CMAKE_CXX_FLAGS}")
 endif()
 
 set(PYTHON_VERSIONS