boblight: libboblight.so has to be in lib not lib.private

[mglae]

script.xbmc.boblight require libboblight.so in lib path to be found from Python.

See https://forum.libreelec.tv/thread/28505-boblight-not-working-on-12-0-anymore/?postID=191714#post191714

Only build tested because using boblight myself

Backport of #8880