Always clear EC groups and points on free.

Always clear EC groups and points on free.

Rather than sometimes clearing, turn the free functions into ones that
always clear (as we've done elsewhere). Turn the EC_GROUP_clear_free() and
EC_POINT_clear_free() functions into wrappers that call the *_free()
version. Do similar for the EC_METHOD implementations, removing the
group_clear_finish() and point_clear_finish() hooks in the process.

ok tb@