egl: Make sure highest possible GL version is created

egl: Make sure highest possible GL version is created

The EGL spec states:

    The context returned must be the specified version, or a later
    version which is backwards compatible with that version.
    Even if a later version is returned, the specified version
    must correspond to a defined version of the client API.

GTK has so far been relying on EGL implementations returning a
later version, because that is what Mesa does.
But ANGLE does not do that and only provides the minimum version, which
means Windows EGL has been forced to use a lower EGL version for no
reason.

So fix this and try versions in order from highest to lowest.