[$] System-call wrappers for glibc

The GNU C Library has long had a reputation for being hostile to theaddition of wrappers for new Linux system calls; that has resulted in manysystem calls being unsupported by the library for years. That situation ischanging, though. During the Toolchain microconference at the 2019 LinuxPlumbers Conference, Maciej Rozycki talked about glibc's new attitudetoward system-call wrappers, but also served notice that there is stillsignificant work to do for the addition of any new system call.