package/poco: bump to version 1.6.1

Also:
  * switch from sourceforge to github
  * remove hash (github-helper)
  * remove upstream applied patches
  * re-number remaining patches
  * add patch to fix build issue with `--bundled` config option

[Thomas: really remove hash file, since we're fetching from Github.]

Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>