abi: Drop libcidn.so.1
This is an implementation detail of glibc support for internationalized domain names and does not appear to be linked directly by applications, so it is not really part of the ABI of the Steam Runtime. In newer versions of glibc, libidn2.so.0 is dlopened instead.
kisak pointed out that this is logged on Fedora and Arch with @timo's 20190909 test Steam client:
Unable to find the library: libcidn.so.1: cannot open shared object file: No such file or directory
We'd probably see the same thing on other recent distros like Debian 10.
We might need to give libcrypt.so.1 and libnsl.so.1 the same treatment (they are not found on Fedora for at least one word size), but I'm holding off on doing those because I know they are sometimes directly linked by executables. They were historically part of glibc, but in very recent versions it is possible to break them off into libxcrypt
and libnsl
source packages. I know some Debian developers have been looking into packaging libxcrypt
separately for Debian 11, and I assume Fedora are ahead of us in this respect.