audio/wavpack: Update to 5.9.0
Add source URL to WWW, since this is what devs really want.
Remove cmake:testing; test target has been failing for a while.
This needs more investigation.
Remove unused WAVPACK_BUILD_DOCS from CMAKE_ARGS. Project transitioned
to WAVPACK_INSTALL_DOCS, but disabling this would disable installation
of the manpages, which is not the desired effect.