dhclient: suppress -Werror=old-style-definition for gcc 14 compat

Author: simonswine

pkgs/dhclient/default.nix

@@ -64,6 +64,7 @@ stdenv.mkDerivation rec {
     "-Wno-error=stringop-truncation"
     "-Wno-error=format-overflow"
     "-Wno-error=stringop-overflow=8"
+    "-Wno-error=old-style-definition"
   ];
 
   installFlags = [ "DESTDIR=\${out}" ];