Make the corresponding change that was made for byval in
b7141207a483d39b99c2b4da4eb3bb591eca9e1a. Like byval, this requires a
bulk update of the test IR tests to include the type before this can
be mandatory.
4c5a93bd landed adjustment to handle C++20 no_unique_address attribute
correctly, clang treats empty members in aggregate type differently if
having this attribute. This commit adds necessary test for PowerPC
target to reflect this change.