LCC, Elbrus: Deal with broken tests on old libc and support LCC 1.21 too

Following up !9099 (merged), I checked if any tests occasionally fail when we have old broken libc on Elbrus, and figured out which ones to exclude in that case. Under heavy load, tests tend to fail more often, and so I found five such tests. I hope no other test will fail because of that reason. Also, during this, I compared this behavior to even older Elbrus distro with LCC 1.21, and to do that, I implemented LCC 1.21 support in CMake.