Remove unused local variable.

Signed-off-by: Keith Rothman <537074+litghost@users.noreply.github.com>
diff --git a/vpr/src/route/check_route.cpp b/vpr/src/route/check_route.cpp
index e602ee4..e52e2ce 100644
--- a/vpr/src/route/check_route.cpp
+++ b/vpr/src/route/check_route.cpp
@@ -811,8 +811,6 @@
 //
 //We treat any configurable stubs as an error.
 void check_net_for_stubs(ClusterNetId net) {
-    auto& route_ctx = g_vpr_ctx.mutable_routing();
-
     StubFinder stub_finder;
 
     bool any_stubs = stub_finder.CheckNet(net);