Revert "[Libomp] Do not error on undefined version script symbols"

This reverts commit 096f93e7.

Revert "[Libomptarget] Make the plugins ingore undefined exported symbols"

This reverts commit 3f62314c.

Revert "[LLD] Enable --no-undefined-version by default."

This reverts commit 7ec8b0d1.

Three commits are reverted because of the current omp build fail
with GNU ld. See discussion here: https://reviews.llvm.org/rG096f93e73dc3