Remove assertions that could be triggered by bad data. (#3469)

When two consecutive nodes have identical coordinates, there is no valid
bearing.  For now, make equal nodes have bearing 0.

Full fix still needs to be done via https://github.com/Project-OSRM/osrm-backend/issues/3470.

unit_tests/library/tile.cpp

@@ -32,7 +32,7 @@ BOOST_AUTO_TEST_CASE(test_tile)
     const auto rc = osrm.Tile(params, result);
     BOOST_CHECK(rc == Status::Ok);
 
-    BOOST_CHECK_EQUAL(result.size(), 114091);
+    BOOST_CHECK_EQUAL(result.size(), 114098);
 
     protozero::pbf_reader tile_message(result);
     tile_message.next();