[coroutine] Salvage dbg.values in the original function as well

D97673 implemented salvaging o dbg.value inside coroutine funclets, but
left the original function untouched. Before, only dbg.addr and dbg.decl
would get salvaged.

D121324 implemented salvaging of dbg.addr and dbg.decl in the original
function as well, but not of dbg.values.

This patch unifies salvaging in the original function and related
funclets, so that all intrinsics are salvaged in all functions. This is
particularly useful for ABIs where the original function is also
rewritten to receive the frame pointer as an argument.

Differential Revision: https://reviews.llvm.org/D148745