package/wavpack: security bump to version 5.2.0

package/wavpack: security bump to version 5.2.0

- Switch to github to get latest version
- Drop patches (already in version)
- Fix CVE-2018-19840: The function WavpackPackInit in pack_utils.c in
  libwavpack.a in WavPack through 5.1.0 allows attackers to cause a
  denial-of-service (resource exhaustion caused by an infinite loop) via
  a crafted wav audio file because WavpackSetConfiguration64 mishandles
  a sample rate of zero.
- Fix CVE-2018-19841: The function WavpackVerifySingleBlock in
  open_utils.c in libwavpack.a in WavPack through 5.1.0 allows attackers
  to cause a denial-of-service (out-of-bounds read and application
  crash) via a crafted WavPack Lossless Audio file, as demonstrated by
  wvunpack.
- Add hash for license file

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>