Bug#787453: libdata-alias-perl: FTBFS with perl 5.22

[Zefram]

Niko Tyni wrote:
>However, building Data-Alias-1.19 with clang works even on our packaged
>perl 5.22.0-4. So the perl build doesn't seem to matter that much.

Thanks, that's a very useful set of results.  Compiler used to build
D-A matters.  It must be doing something hacky at the C language level of
which I was not previously aware.  I can probably track it down from here.

-zefram