gdbserver/event-loop.c: type mismatch

Building with C++ catches a buglet here:

../../../src/gdb/gdbserver/event-loop.c:205:19: warning: invalid conversion from ‘gdb_client_data {aka void*}’ to ‘void**’ [-fpermissive]
   event_ptr->data = data;
                   ^

This works in practice because gdb_client_data is a pointer already
(hence in C we get an implicit conversion), and nothing deferences the
pointer.  It's passed from client at event registration/creation time,
only to pass straight back to client callback.

Well, that and nothing in gdbserver uses the event data anyway.

gdb/gdbserver/ChangeLog:
2015-07-10  Pedro Alves  <palves@redhat.com>

	* event-loop.c (struct callback_event) <data>: Change type to
	gdb_client_data instance instead of gdb_client_data pointer.
	(append_callback_event): Adjust.

gdb/gdbserver/ChangeLog

@@ -1,3 +1,9 @@
+2015-07-10  Pedro Alves  <palves@redhat.com>
+
+	* event-loop.c (struct callback_event) <data>: Change type to
+	gdb_client_data instance instead of gdb_client_data pointer.
+	(append_callback_event): Adjust.
+
 2015-07-10  Pierre Langlois  <pierre.langlois@arm.com>
 
 	* linux-aarch64-low.c: Add comments for each linux_target_ops

gdb/gdbserver/event-loop.c

@@ -130,7 +130,7 @@ struct callback_event
   {
     int id;
     callback_handler_func *proc;
-    gdb_client_data *data;
+    gdb_client_data data;
     struct callback_event *next;
   };
 
@@ -249,7 +249,7 @@ process_callback (void)
   if (event_ptr != NULL)
     {
       callback_handler_func *proc = event_ptr->proc;
-      gdb_client_data *data = event_ptr->data;
+      gdb_client_data data = event_ptr->data;
 
       /* Remove the event before calling PROC,
 	 more events may get added by PROC.  */