Issue #14252: Fix subprocess.Popen.terminate() to not raise an error under Windows when the child process has already exited.

Issue #14252: Fix subprocess.Popen.terminate() to not raise an error under Windows when the child process has already exited.

It now reports if configure and pyconfig.h.in weren't regenerated but
configure.in was changed.

(PPC buildbot)

Close #14210: add command argument completion to pdb: complete file names, global/local variables, aliases

Fixed the problem and added some tests. Closes #14178