For memcpy and memcmp, we need to multiply by the element size,
otherwise we're copying and comparing only a fraction of the buffer.
For decorrelate_sr, the buffer p1 is the one that is mutated;
copy and check p1 instead of p2.
For decorrelate_sm, both buffers are mutated, so copy and check
both of them.
For decorrelate_sm, the memcpy initialization of p1 and p1_2 was
reversed - p1 is filled with randomize, but then memcpy copies from
p1_2 to p1. As p1_2 is uninitialized at this point, clang concluded
that the copy was bogus and omitted it entirely, triggering failures
in this test on x86 (where there was an existing assembly implementation
to test).
Signed-off-by: Martin Storsjö <martin@martin.st>