Revert "[DwarfDebug] Support emitting function-local declaration for a lexical...

Revert "[DwarfDebug] Support emitting function-local declaration for a lexical block" & dependent patches

This patch causes invalid DWARF to be generated in some cases of LTO +
Split DWARF - follow-up on the original review thread (D113741) contains
further detail and test cases.

This reverts commit 75b622a7.
This reverts commit b6ccca21.
This reverts commit 514d3744.