platform: parse routes of any type to handle replace

When you issue

  ip route replace broadcast 1.2.3.4/32 dev eth0

then this route may well replace a (unicast) route that we have in
the cache.

Previously, we would right away ignore such messages in
_new_from_nl_route(), which means we miss the fact that a route gets
replaced.

Instead, we need to parse the message at least so far, that we can
detect and handle the replace.

src/libnm-platform/nm-linux-platform.c

@@ -3787,15 +3787,6 @@ _new_from_nl_route(const struct nlmsghdr *nlh, gboolean id_only, ParseNlmsgIter
     else
         return NULL;
 
-    if (!NM_IN_SET(rtm->rtm_type,
-                   RTN_UNICAST,
-                   RTN_LOCAL,
-                   RTN_BLACKHOLE,
-                   RTN_UNREACHABLE,
-                   RTN_PROHIBIT,
-                   RTN_THROW))
-        return NULL;
-
     if (nlmsg_parse_arr(nlh, sizeof(struct rtmsg), tb, policy) < 0)
         return NULL;
 
@@ -5331,6 +5322,17 @@ ip_route_is_alive(const NMPlatformIPRoute *route)
         return FALSE;
     }
 
+    if (!NM_IN_SET(nm_platform_route_type_uncoerce(route->type_coerced),
+                   RTN_UNICAST,
+                   RTN_LOCAL,
+                   RTN_BLACKHOLE,
+                   RTN_UNREACHABLE,
+                   RTN_PROHIBIT,
+                   RTN_THROW)) {
+        /* Certain route types are ignored and not placed into the cache. */
+        return FALSE;
+    }
+
     return TRUE;
 }