[$] Race-free process creation in the GNU C Library

The pidfd API has been added to the kernelover the last several years to provide a race-free way for processes torefer to each other. While the GNU C Library (glibc) gainedbasic pidfd support with the 2.36 release in 2022, it still lacks acomplete solution for race-free process creation. Thispatch set from Adhemerval Zanella seems likely to fill that gap in thenear future, though, with an extension to the posix_spawn()API.