GDK-Win32: Fix drag surface positioning

Adjust the coordinates of where the drag surface using
gdk_win32_surface_get_root_coords(), so that drag surfaces are
positioned correctly.

Fixes issue #3798.
13 jobs for fix-3798 in 30 minutes and 3 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  .Pre
failed #1342475
allowed to fail
style-check-diff

00:03:59

 
  Build
passed #1342476
fedora-x86_64

00:09:08

passed #1342478
installed-tests

00:05:52

passed #1342480
macos
macos

00:11:52

passed #1342479
win32-ps
msys2-mingw64

00:08:30

passed #1342477
release-build

00:08:14

passed #1342481
win32-ps
vs2017-x64

00:15:17

 
  Analysis
failed #1342483
asan allowed to fail
asan-build

00:09:08

passed #1342482
static-scan

00:13:12

 
  Docs
passed #1342484
reference

00:11:09

 
  Flatpak
manual #1342485
flatpak allowed to fail manual
flatpak-manual:demo
manual #1342487
flatpak allowed to fail manual
flatpak-manual:icon-browser
manual #1342486
flatpak allowed to fail manual
flatpak-manual:widget-factory
 
Name Stage Failure
failed
style-check-diff .Pre
                                      surface->x,
surface->y,
- &surface->x,
+ &surface->x,
&surface->y);
gdk_win32_surface_resize (surface, width, height);
gdk_win32_surface_show (surface, FALSE);
Cleaning up file based variables
ERROR: Job failed: exit code 1
failed
asan-build Analysis
 - css: 214 total, 214 pass, 0 fail
Processing gtk suite a11y:
- a11y: 22 total, 22 pass, 0 fail
Processing gtk suite tools:
- tools: 4 total, 4 pass, 0 fail
Processing gtk suite reftest:
- reftest: 131 total, 130 pass, 1 fail
Cleaning up file based variables
ERROR: Job failed: exit code 1