GDK W32: Remove stacking functions

Stacking functions enforce non-native stacking behaviour that is
mostly unneeded, and doing so introduces bugs and complicates things.
7 jobs for w32-transient-ordering-rollback in 28 minutes and 44 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #687375
debian-meson

00:05:36

passed #687372
fedora-autotools

00:06:52

manual #687373
allowed to fail manual
fedora-distcheck
passed #687374
fedora-meson

00:07:00

manual #687377
win32 allowed to fail manual
msys2-mingw32-autotools
passed #687376
win32
msys2-mingw32-meson

00:18:18

 
  Docs
passed #687378
reference

00:10:26