Bug#1040504: dh-puredata: armhf externals use wrong extension

[IOhannes m zmoelnig <umlaeute@debian.org>]

Package: dh-puredata
Version: 3.1.0
Severity: normal

Dear Maintainer,

double-precision externals built on armhf use .linux-armhf-64.so as extenion.
I think they should use .linux-armv7-64.so instead.

while fixing this, also check other CPUs (e.g. PowerPC)