egl: rewrite entrypoints check

egl: rewrite entrypoints check

Part of the effort to replace shell scripts with portable python scripts.
I could've used a trivial `assert lines == sorted(lines)`, but this way
the caller is shown which entrypoint is out of order.

Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by Dylan Baker <dylan@pnwbakers.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>