media-libs/raspberrypi-userland: add support for no-multilib profiles

[teapot9]

No-multilib profiles use lib and not lib64. Use get_libdir to detect which directory to use. This fixes #26.

[sakaki-]

30 Oct 2020: sadly, due legal obligations arising from a recent change in my 'real world' job, I must announce I am standing down as maintainer of this project with immediate effect. For the meantime, I will leave the repo up (for historical interest, and since the ebuilds etc. may be of use for others looking to take forward Gentoo on 64-bit RPi systems); however, there will be no further updates to the underlying binhost etc., nor will I be accepting / actioning further pull requests or bug reports from this point. Email requests for support will also have to be politely declined, so, please treat this as an effective EOL notice.

For further details, please see my post here.

Many thanks for your interest in this project!

With sincere apologies, sakaki ><