[NFC] Add test of sized deallocation for coroutines

[NFC] Add test of sized deallocation for coroutines

[dcl.fct.def.coroutine]p12 says:

> If both a usual deallocation function with only a pointer parameter
> and a usual deallocation function with both a pointer parameter and a
> size parameter are found, then the selected deallocation function
> shall be the one with two parameters.

However, the sized deallocation function is disabled by default for ABI
reasons. This leads the sentence never get tested and covered. This
commit tries to add a test for it