src: fix compiler warning in env.cc

     ../src/env.cc:1227:22: error: lambda capture 'this' is not used [-Werror,-Wunused-lambda-capture]
      ForEachBaseObject([this](BaseObject* obj) {
                     ^~~~

PR-URL: #35547
Backport-PR-URL: #38786
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Shelley Vohr <codebytere@gmail.com>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>

Author: addaleax

src/env.cc

@@ -1064,7 +1064,7 @@ void Environment::VerifyNoStrongBaseObjects() {
 
   if (!options()->verify_base_objects) return;
 
-  ForEachBaseObject([this](BaseObject* obj) {
+  ForEachBaseObject([](BaseObject* obj) {
     if (obj->IsNotIndicativeOfMemoryLeakAtExit()) return;
     fprintf(stderr, "Found bad BaseObject during clean exit: %s\n",
             obj->MemoryInfoName().c_str());