from the fnmatch tests.
I'm committing the generated files because I don't like a build dependency
for the sh(1) tests, and they are small and will not change much.
* retry various system calls on EINTR
* retry the rest after a short read (common if there is more than about 1K
of output)
* block SIGCHLD like system(3) does (note that this does not and cannot
work fully in threaded programs, they will need to be careful with wait
functions)
PR: 90580