Bug#566587: FTBFS: tests fail

[Jonathan Yu]

Hi all:

I have confirmed this bug with sbuild/schroot + amd64. As with
Salvatore, I did not have the issue with x86.

I'm hesitant to apply gregoa's patch because it seems like it might
have problems where machines *cannot* left-shift 62 bits... If the
register is only 32-bits wide (as with i386 on older machines), then
this may result in data falling off the end (and $low4bytes will be
zeroed out).

I think we can look into something with the Config module, which will
tell us various info that perl -V tells us, such as:
    intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678

If we can confirm gregor's fix works when intsize=4, longsize=4,
ptrsize=4 (ie, older 32-bit only processors) then we can consider
that. Otherwise, I'd prefer to use $Config to determine information
about the architecture and select the appropriate bit twiddling.

(Better yet, it seems like there should be an upstream module that
does this sort of thing, like "keep only X bits of data" or
something...)

Cheers,

Jonathan