Fixes: https://gitlab.gnome.org/GNOME/vte/-/issues/2835
(cherry picked from commit ef34accf)

vte_pty_spawn_finish() takes a GPid*, not a pid_t*, which are apparently
different types on some 32-bit systems.

Patch by Marcel Telka.

Fixes: https://gitlab.gnome.org/GNOME/vte/-/issues/2833
(cherry picked from commit 9dbb6fd2)

Fixes: https://gitlab.gnome.org/GNOME/vte/-/issues/2843
(cherry picked from commit b0fbf743)

... which would prevent copy elision.

(cherry picked from commit 9d2e66fc)

(cherry picked from commit e4f4ca72)