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

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

This has broke following LLDB buildbots:

https://lab.llvm.org/buildbot/#/builders/17/builds/14984
https://lab.llvm.org/buildbot/#/builders/96/builds/15928
https://lab.llvm.org/buildbot/#/builders/68/builds/23600

This reverts commit 62a6b9e9.