[Bug gcov-profile/110827] C++20 coroutines aren't being measured by gcov

[mwd at md5i dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110827

--- Comment #4 from Michael Duggan <mwd at md5i dot com> ---
I should be more explicit.  The `std::cout` line in the example is just a
placeholder for "does some work here," and this example is specifically the
simplest version of a coroutine I could come up with that would demonstrate the
problem.  When I initially encountered this problem, I was doing coverage
testing that included a coroutine that was over 70 lines long, includes lots of
loops and branching, and exited and re-entered multiple times via `co_yield`. 
I wanted to know if my test programs properly covered all of the branches.  It
is not enough to know how many times the coroutine itself is called.