Bug#752026: libpdl-stats-perl: FTBFS on arm*

[Edmund Grimley Evans]

It seems this can be fixed on arm64 by replacing "-1" with "2" in
these two lines in Kmeans/kmeans.pp:

    ($_tmp = $var_a($ibad, )) .= -1;
    $var_a->inplace->setvaltobad(-1);

However, I don't know whether that's the right way to fix the problem
as I don't know how Perl's and PDL's type system is supposed to work.
In particular, does it suggest that there is something wrong in the
"pdl" package that using "-1" in this code results in different
behaviour on different architectures, or is undefined behaviour
expected in a case like this?

As far as I can tell from a quick web search, "byte" is supposed to be an
unsigned char, so the use of "-1" in the code quoted above is at least
a bit confusing.