chore(CMakeLists.txt): deal correctly with no debug flags

linphone-desktop/CMakeLists.txt

@@ -60,15 +60,16 @@ if(NOT WIN32)
     set(CUSTOM_FLAGS "${CUSTOM_FLAGS} -Wsuggest-override -Werror=suggest-override")
   endif()
 endif()
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${CUSTOM_FLAGS} -DNDEBUG -DQT_NO_DEBUG")
-set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -DDEBUG -DQT_QML_DEBUG -DQT_DECLARATIVE_DEBUG")
 
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${CUSTOM_FLAGS}")
 # See: http://stackoverflow.com/a/1372836
 if(WIN32)
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -D_WINSOCKAPI_")
-  set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -D_WINSOCKAPI_")
 endif()
 
+set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -DNDEBUG -DQT_NO_DEBUG")
+set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -DDEBUG -DQT_QML_DEBUG -DQT_DECLARATIVE_DEBUG")
+
 # ------------------------------------------------------------------------------
 # Define packages, libs, sources, headers, resources and languages.
 # ------------------------------------------------------------------------------