[Warnings] Removed Unused Variables When Capnproto is Disabled

A few variables were left unused when CAPNPROTO was disabled which were
giving warnings on the CI. Commented these unused variables out.

Author: AlexandreSinger

vpr/src/route/router_lookahead_extended_map.cpp

@@ -606,10 +606,10 @@ float ExtendedMapLookahead::get_expected_cost(
 
 #ifndef VTR_ENABLE_CAPNPROTO
 
-void ExtendedMapLookahead::read(const std::string& file) {
+void ExtendedMapLookahead::read(const std::string& /*file*/) {
     VPR_THROW(VPR_ERROR_ROUTE, "MapLookahead::read not implemented");
 }
-void ExtendedMapLookahead::write(const std::string& file) const {
+void ExtendedMapLookahead::write(const std::string& /*file*/) const {
     VPR_THROW(VPR_ERROR_ROUTE, "MapLookahead::write not implemented");
 }