default or selected kernelversion does not have config value CONFIG_HAVE_EXIT_THREAD.
Result is shown for kernelversion 6.9-rc1

CONFIG_HAVE_EXIT_THREAD (not configurable)

configname: CONFIG_HAVE_EXIT_THREAD

Linux Kernel Configuration
└─>General architecture-dependent options
└─>HAVE_EXIT_THREAD
In linux kernel since version 4.1 (release Date: 2015-06-21)  
An architecture implements exit_thread.