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.
