steamrt-container-host-compat: Don't create symlinks to ld.so
dpkg-shlibdeps in at least SteamRT 1 'scout' gets confused if it finds ld.so in an unexpected directory. We'll have to create the symlinks in the Platform and SDK runtimes instead.
I've tested this and I'm going to merge it unreviewed, but I'm opening a MR to keep track.
This also needs changing in steamrt/soldier
and steamrt/heavy
(the same change applies fine).