Hello, I have been playing around with Doom's source code, the 90s one, and I have noticed that it has a header included named errnos.h that I have recently learned that it was actually present in glibc beginning from 2.0.0 (I think) until 2.0.7. Could anyone shed light on why it was added to glibc and later removed?

https://sources.debian.org/src/glibc/2.0.7t-1/sysdeps/unix/sysv/linux/errnos.h/
https://github.com/id-Software/DOOM/blob/master/linuxdoom-1.10/i_video.c#L49