Simply route length generation code.

The old code had logic to use a shorter path length if we didn't
have enough nodes. But we don't support 2-node networks anwyay.

Fix for #9926.  I'm not calling this a bugfix on any particular
version, since a 2-node network would fail to work for you for a lot
of other reasons too, and it's not clear to me when that began, or if
2-node networks would ever have worked.

changes/bug9926

@@ -0,0 +1,6 @@
+  o Minor bugfixes:
+    - Remove some old fallback code designed to keep Tor clients working
+      in a network with only two working nodes. Elsewhere in the code we
+      have long since stopped supporting such networks, so there wasn't
+      much point in keeping it around. Fixes bug 9926.
+