[coro async] Disable lifetime.start sinking for ABI::Async and ABI::Retcon
It does not handle loops correctly i.e it moves the lifetime.start
intrinsic into a loop rendering the stack object as not alive for part
of the loop.
```
entry:
%obj = alloca i8
lifetime.start(%obj)
br loop
loop:
coro.suspend()
escape(%obj)
cond_br %cond, label %exit, label loop
br loop
exit:
lifetime.end(%obj
```
After sinking:
```
entry:
%obj = alloca i8
br loop
loop:
coro.suspend()
lifetime.start(%obj)
escape(%obj)
cond_br %cond, label %exit, label loop
br loop
exit:
lifetime.end(%obj
```
rdar://83411917
Differential Revision: https://reviews.llvm.org/D110953
llvm-project
64ba9dd9 - [coro async] Disable lifetime.start sinking for ABI::Async and ABI::Retcon
