mitigate lto compiler bug with lto

llarp/config/config.cpp

@@ -748,16 +748,15 @@ namespace llarp
             m_bind.setPort(53);
         });
 
-    conf.defineOption<std::string>(
+    conf.defineOption<fs::path>(
         "dns",
         "add-hosts",
         ClientOnly,
         Comment{"Add a hosts file to the dns resolver", "For use with client side dns filtering"},
-        [=](std::string arg) {
-          if (arg.empty())
+        [=](fs::path path) {
+          if (path.empty())
             return;
-          fs::path path{arg};
-          if (not exists(path))
+          if (not fs::exists(path))
             throw std::invalid_argument{
                 stringify("cannot add hosts file ", path, " as it does not seem to exist")};
           m_hostfiles.emplace_back(std::move(path));