Revert "musl: meson: add libutmps support"

Revert "musl: meson: add libutmps support"

This reverts commit bf9bc5beb090bb35184caf34cc641e708615e83a.

libutmps does not support utmpxname(), the function always fails
with ENOSYS, and always uses their own file.
However, our code relies on the funtion needs to succeed.

Let's revert the change now, and revisit later when musl users
request to support libutmps.