tests: fix tests for 1a211cb (missing well-known)

tests: fix tests for 1a211cb (missing well-known)

Fix tests/aspathtest.c again, this time by including a NEXT_HOP
attribute (which is out of correct order with AS_PATH, but that doesn't
matter here.)  This satisfies bgp_attr_check(), which after 1a211cb
refuses updates without nexthop attribute.

Fixes: 1a211cb ("one more fix for tightening of check for missing well-known attributes")
Cc: Paul Jakma <paul@opensourcerouting.org>
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
(cherry picked from commit 143637198e333f0c822766b38f9d8cfe75c04e21)