8228448: Jconsole can't connect to itself

Additions done to allow jconsole to connect to itself

Reviewed-by: erikj
diff --git a/make/launcher/Launcher-jdk.jconsole.gmk b/make/launcher/Launcher-jdk.jconsole.gmk
index 6205ae6..575b9e0 100644
--- a/make/launcher/Launcher-jdk.jconsole.gmk
+++ b/make/launcher/Launcher-jdk.jconsole.gmk
@@ -28,7 +28,8 @@
 $(eval $(call SetupBuildLauncher, jconsole, \
     MAIN_CLASS := sun.tools.jconsole.JConsole, \
     JAVA_ARGS := --add-opens java.base/java.io=jdk.jconsole \
-		 -Djconsole.showOutputViewer, \
+		 -Djconsole.showOutputViewer \
+		 -Djdk.attach.allowAttachSelf=true, \
     CFLAGS_windows := -DJAVAW, \
     LIBS_windows := user32.lib, \
 ))