build(core) hide target version warning on JDK 21+

config/build-definitions.xml

@@ -203,7 +203,8 @@ This script is included in /build.xml and /config/update-dependencies.xml.
     <presetdef name="lwjgl.javac">
         <javac sourcepath="" debug="yes" source="8" target="8" encoding="UTF-8" includeantruntime="false">
             <compilerarg line='--boot-class-path "${env.JAVA8_HOME}/jre/lib/rt.jar"' if:set="set-boot-class-path"/>
-            <compilerarg value="-Xlint:all"/>
+            <compilerarg value="-Xlint:all" unless:set="jdk21"/>
+            <compilerarg line="-Xlint:all,-options" if:set="jdk21"/>
             <compilerarg value="-XDignore.symbol.file"/> <!-- Suppresses internal API (e.g. Unsafe) usage warnings -->
         </javac>
     </presetdef>