[libc][errno] Remove previously added errno numbers (#92163)

Introduced in https://github.com/llvm/llvm-project/pull/91150. Not
needed anymore as https://github.com/llvm/llvm-project/pull/92041 fixed
the root cause. `ENAMETOOLONG` and `EOVERFLOW` are well defined in
`<linux/errno.h>`.

Post mortem: Due to the previously missing inclusion of
`<linux/errno.h>` (fixed with
https://github.com/llvm/llvm-project/pull/92041), I misinterpreted an
undefined macro issue during the development of
https://github.com/llvm/llvm-project/pull/91150 as being caused by a
missing definition rather than by the missing inclusion of the linux
header. I realized too late that `ENAMETOOLONG` and `EOVERFLOW` were
correctly defined in `<linux/errno.h>` and that it was my missing
inclusion that caused the problem.