In EGLQueryString, it is now valid to query EGL_EXTENSIONS
with a display set to EGL_NO_DISPLAY, so the function
should proceed without returning an error in these cases.

Change-Id: I76ccd4f98f3d4180268b6b85b5b04a19bea59977
Reviewed-on: https://swiftshader-review.googlesource.com/9948Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>