[PassManager][Coroutine] Run passes under -O0 conditionally and run GlobalDCE

[PassManager][Coroutine] Run passes under -O0 conditionally and run GlobalDCE

CoroSplit lowers various coroutine intrinsics. It's a CGSCC pass and
CGSCC passes don't run on unreachable functions. Normally GlobalDCE will
come along and delete unreachable functions, but we don't run GlobalDCE
under -O0, so an unreachable function with coroutine intrinsics may
never have CoroSplit run on it.

This patch adds GlobalDCE when coroutines intrinsics are present. It
also now runs all coroutine passes conditional when coroutine intrinsics
are present. This should also solve the -O0 regression reported in
D105877 due to LazyCallGraph construction.

Fixes https://github.com/llvm/llvm-project/issues/54117

Reviewed By: ChuanqiXu

Differential Revision: https://reviews.llvm.org/D122275