git commit for WITH_DETECT_TZ_CHANGES breaks date, et al

[Michael Butler via freebsd-current]

After commit ddedf2a11eb20af1ee52cb3da70a57c21904af8f date fails to 
recognize any configured timezone when WITH_DETECT_TZ_CHANGES is not set.

For example ..
imb@vm01:/home/imb> date
Tue Sep 14 01:25:57  2021

Every other daemon also thinks it's running in UTC+0 :-(

When libc is recompiled with WITH_DETECT_TZ_CHANGES=yes in 
/etc/src.conf, the output is (for me) ..

imb@vm01:/usr/src/lib/libc> date
Mon Sep 13 21:28:29 EDT 2021

        imb