You copyed the contents only without the linux32 folder,? only the contents i think it depends on distro mabye i was wrong you need to copy to /home/username/.steam/sdk32
Any reason to run a desktop based Distro to run Server's ?
If it's indeed a GLIBC / GCC error, i think you should compile the GCC 7 for your distibution
https://forums.alliedmods.net/showthread.php?t=336183
Seems this fixed on ubuntu, but you can try