d3d11window: Protect registration/creation of WIN32 window

Querying existing window class info and creation of window object
should be protected since they are not thread safe.
21 jobs for master in 76 minutes and 24 seconds (queued for 28 seconds)
Status Job ID Name Coverage
  Preparation
passed #697152
gst indent

00:00:30

passed #697151
manifest

00:00:29

 
  Build
passed #697162
build cerbero cross-android universal

00:16:26

manual #697166
gst-ios-12.2 allowed to fail manual
build cerbero cross-ios universal
passed #697163
build cerbero cross win32

00:09:38

passed #697164
build cerbero cross win64

00:07:00

passed #697161
build cerbero fedora x86_64

00:07:39

passed #697165
gst-macos-10.14
build cerbero macos x86_64

00:06:42

passed #697157
build clang fedora x86_64

00:07:55

passed #697153
build fedora x86_64

00:05:49

passed #697160
1607 windows docker
build msys2

00:15:36

passed #697154
build nodebug fedora x86_64

00:03:46

passed #697155
build static fedora x86_64

00:13:15

passed #697156
build static nodebug fedora x86_64

00:05:47

passed #697158
1607 windows docker
build vs2017 amd64

00:15:58

passed #697159
1607 windows docker
build vs2017 x86

00:13:43

 
  Test
passed #697167
check fedora

00:03:29

passed #697168
integration testsuites fedora

00:39:41

 
  Integrate
passed #697169
cross-android universal examples

00:07:20

manual #697171
gst-ios-12.2 allowed to fail manual
cross-ios universal examples
passed #697170
documentation

00:04:42