* Enable ANGLE's desktop GL backend

Only the D3D and GLES backends were available, but getting desktop GL to
work is trivial.

The Vulkan backend would be a much bigger task, unfortunately.

* x-add-version

Co-authored-by: Billy Robert O'Neal III <bion@microsoft.com>

* Fix import lib prefixes

* Fix mingw build

* x-add-version

* [angle] Update to chromium/4472

* Run x-add-version angle

* Avoid exluding EGL/eglext_angle.h from ANGLE and add egl_loader_autogen.cpp/h that were not properly added.

* Add port version to ANGLE port.

* Ran vcpkg x-add-version --overwrite-version angle.

* Add egl renderer to list of files compiled for linux

* Update Control File as per request from vcpkg reviewers

Co-authored-by: Ankur Verma <ankurv@localhost.localdomain>

* [angle] update for gcc 10 compatibility

* [angle] macos fix

* [angle] Fix UWP builds

Co-authored-by: Igor Kostenko <ikostenko@perforce.com>

* update opengl and install all headers

* improve angle

* update egl-registry

* fix osx regression

* update baseline.

* fix uwp regressions

* fix osx and linux regression

* add encoding patch

* bump glad control

* rechdeck gl visibility from native build

* removed unnecessary commented code

* add GL_VISIBILITY to the exported targets

Co-authored-by: dan-shaw <51385773+dan-shaw@users.noreply.github.com>

* [angle] Update to 2019-12-31

* [angle] install *.inc files

* [angle] Update to the latest commit.

* Fix build linux.

* Update CMakeList.txt and linux patch.

* update to latest

* Disable OpenGL deprecation warnings

* Update CMakeLists.txt

* include objective c files

* don't filter any files out of common (same as upstream autotools)

* drop unit tests so we don't bring in gtest

* add filter mode

* add back filter except for android