080-Util-Linux: Why do we need ``ttydefaults.h``?

[takusuman]

I'm building Util-Linux for a Musl-LFS fork, Copacabana --- I think I've cited it here before, in some commits and contributions that I brought from it to Musl-LFS --- and, looking between both the Musl-LFS instructions and other distributions' build scripts for base system Util-Linux, I found the same header being sourcered and used.
The question is: why do we need ttydefaults.h? I've tried to build Util-Linux without regenerating them and it built fine.

[takusuman]

And, not related to this question, I've discovered that utmpx wouldn't work at configure if we have LDFLAGS set as '-static'.