Revert "[SelectionDAG] Add pcsections recursively on SDNode values"

Revert "[SelectionDAG] Add missing setValue calls in visitIntrinsicCall"

This reverts commit 0c64e1b6.
This reverts commit 1142e6c7.

It spuriously added !pcsections where they shouldn't be. See added test
case in test/CodeGen/X86/pcsections.ll as an example. The reason is that
the SelectionDAG chains operations in a basic block as "operands"
pointing to preceding instructions. This resulted in setting the
metadata on _all_ instructions preceding the one that should have the
metadata.

Reverting for now because the semantics of !pcsections was completely
buggy now.