[clang] [Clang] Propagate elide safe context through [[clang::coro_must_await]] (PR #108474)

[Chuanqi Xu via cfe-commits]

================
@@ -249,7 +249,10 @@ Attribute Changes in Clang
   (#GH106864)
 
 - Introduced a new attribute ``[[clang::coro_await_elidable]]`` on coroutine return types
-  to express elideability at call sites where the coroutine is co_awaited as a prvalue.
+  to express elideability at call sites where the coroutine is invoked under a safe elide context.
+
+- Introduced a new attribute ``[[clang::coro_must_await]]`` on function parameters to
----------------
ChuanqiXu9 wrote:

I don't like the name. The name were saying the entity must be awaited. But the explanation are saying other things. Let's make it more straight forward and precise. e.g, something like `[[clang::coro_must_elide_argument]]`.

https://github.com/llvm/llvm-project/pull/108474