CMake: Remove redundant -DNDEBUG

This reverts a42f1a49a4892fbae168c5c63edb83abd8a10c6d, which should
have been reverted by faced9aa499ece4e5e294cc548f571c450ef1df1.

cmake/macros/Interrogate.cmake

@@ -245,11 +245,6 @@ function(interrogate_sources target output database language_flags)
     endif()
   endforeach(_config)
 
-  # In case the user (or a distro buildsystem) is throwing NDEBUG in by hand:
-  if(CMAKE_CXX_FLAGS MATCHES ".*NDEBUG.*")
-    list(APPEND define_flags "-DNDEBUG")
-  endif()
-
   get_filename_component(output_directory "${output}" DIRECTORY)
   get_filename_component(database_directory "${database}" DIRECTORY)