bug#44743: native-comp: confirm-exit-emacs warns about active processes when compiling

[Stefan Kangas]

Severity: minor

Steps to reproduce, on the native-comp branch:

0. rm -rf ~/.emacs.d/eln-cache
1. emacs -Q
2. C-x C-c
3. Press "y" (I am sure I want to quit)

A prompt is now shown with this text:
"Active processes exist; kill them and exit anyway? (y or n) "

The processes are all native-comp processes.

Expected result: No prompt is shown.  The native-comp processes are
recognized and killed automatically.