My system has libc 5 preinstalled, not glibc 2. Can I still use LinuxThreads?
Yes, but you’re likely to run into some problems, as libc 5 only offers minimal support for threads and contains some bugs that affect multithreaded programs. The versions of libc 5 that work best with LinuxThreads are libc 5.2.18 on the one hand, and libc 5.4.12 or later on the other hand. Avoid 5.3.12 and 5.4.7: these have problems with the per-thread errno variable.