Remove the "If only executable code is distributed..." paragraph from
the license text. Everything now uses a normal MIT license.
The only code from Khronos that's included in libglvnd is the EGL/GL
header and XML files, which do not contain that paragraph.
Fixes https://gitlab.freedesktop.org/glvnd/libglvnd/-/issues/221
Added a test for EGL_EXT_device_enumeration and EGL_EXT_platform_device, plus
dispatching to an EGL extesnion function based on an EGLDeviceEXT handle.
Added two dummy libraries for EGL. They both use the same code, but each one
has a name string that can be used to check which vendor something is
dispatched to.
The dummy library is still incomplete, but more functions will be add later
along with more tests.
The test just creates an EGLDisplay using a dummy platform type, and then
checks to make sure that the display dispatches to the correct vendor library.
Also added a script to set up the test environment, and a file for common
functions and variables for EGL tests.
