An asynchronous name lookup library was added. The proposal was circulated beforehand to get comments. No negative ones came in. Implemented by Ulrich Drepper. The RPC code is now thread safe.
Threads can now use the same service of different services at the same time.
One other change is noting worthwhile. The problem is some code in gcc which was necessary in libc5 but not with glibc. There are many compiler versions which are not working correctly and the configure script is not able to catch them all. If something goes wrong during your compilation first try a different compiler and less aggressive optimizations. In the case of Arm it is suspected that the FPU emulator is broken.