After D98856 these tests will by default break (fatal_error) if any of
the wrong interfaces are used, so there's no longer a need to have a
RUN line that checks for a warning message emitted by the compiler.
This patch adds a bunch of CHECK lines to guard against implicit
conversions of TypeSize -> uint64_t occuring in code-paths that previously
were safe for scalable vectors.
Sander de Smalen