Bug#1016709: pd-lib-builder: provide a dh-sequence-pdlibbuilder

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

Source: pd-lib-builder
Version: 0.6.0-1
Severity: wishlist

Many pd-externals use pd-lib-builder, and the d/rules look all very similar.
It would be great if we could use dh to remove the duplicate work.

1. check if the make-based build system actually uses Makefile.pdlibbuilder
2. add 'PDLIBBUILDER_DIR=/usr/share/pd-lib-builder/ prefix=/usr pkglibdir=$(pkglibdir)'
   to the dh_auto_(clean|build|test|install) invocations
3. autofix permissions of pd-externals
4. possibly remove the extraneous LICENSE.txt files that come with Pd

Also, once we have puredata64 in Debian, this would:
- check which binary package variants are built ('pd-*' vs 'pd64-*)
- automatically build both package kinds (if so requested), using different
  flags

And there should be something like ${Pd:Depends} and ${Pd64:Depends}

check out the dh-sequence-kf5 how to switch the dh-buildsystem via a sequence