If style (A) is the way to go, then for every architecture which does not
support the RTS linker a when-clause must be added.
If style (B) is the way to go, then shouldn't we change all test cases of style
(A) to style (B)?
Personally I prefer style (B) over (A) because it makes it easier to add an
architecture where the RTS linker is not provided. Even if the RTS linker is
provided after some time, then the test case must not be changed. Once
PowerPC64 supports the RTS linker all when-clauses must be removed.