glcontext/wgl: Call wglShareLists from the other context's thread

During wglShareLists() call, the other context should not be
the current in a different thread. That's restriction of wgl.
So calling wglShareLists() in the corresponding other context's thread
seems to the most safe way.
24 jobs for fix-wgl-sharing in 80 minutes and 21 seconds (queued for 15 minutes and 15 seconds)
latest
Status Job ID Name Coverage
  Preparation
passed #517542
gst indent

00:00:35

passed #517541
manifest

00:00:57

 
  Build
passed #517551
build cerbero android universal

00:13:39

passed #517552
build cerbero cross win32

00:09:47

passed #517553
build cerbero cross win64

00:07:35

passed #517550
build cerbero fedora x86_64

00:06:50

manual #517555
gst-ios-12.2 allowed to fail manual
build cerbero ios universal
passed #517554
gst-macos-10.14
build cerbero macos x86_64

00:12:19

passed #517543
build fedora x86_64

00:06:04

passed #517549
docker windows 1607
build msys2

00:14:22

passed #517544
build nodebug fedora x86_64

00:05:56

passed #517545
build static fedora x86_64

00:13:48

passed #517546
build static nodebug fedora x86_64

00:13:17

passed #517547
docker windows 1607
build vs2017 amd64

00:11:08

passed #517548
docker windows 1607
build vs2017 x86

00:11:49

 
  Test
failed #517556
check fedora

00:07:30

canceled #517557
integration testsuites fedora

00:06:26

canceled #517561
valgrind bad

canceled #517558
valgrind base

00:05:17

canceled #517562
valgrind ges

canceled #517559
valgrind good

00:02:15

canceled #517560
valgrind ugly

00:00:34

 
  Integrate
skipped #517563
android universal examples
skipped #517564
documentation
 
Name Stage Failure
failed
check fedora Test
           Total: 3122
Uploading artifacts...
gst-build/build/meson-logs/: found 2 matching files
validate-logs: found 3540 matching files

Uploading artifacts to coordinator... ok
id=517556 responseStatus=201 Created token=j1xUcHsB
Uploading artifacts...
validate-logs/*.xml: found 1 matching files

Uploading artifacts to coordinator... ok
id=517556 responseStatus=201 Created token=j1xUcHsB
ERROR: Job failed: exit code 1