Display names of remote threads

This patch adds support for thread names in the remote protocol, and
updates gdb/gdbserver to use it.  The information is added to the XML
description sent in response to the qXfer:threads:read packet.

gdb/ChangeLog:

	* linux-nat.c (linux_nat_thread_name): Replace implementation by call
	to linux_proc_tid_get_name.
	* nat/linux-procfs.c (linux_proc_tid_get_name): New function,
	implementation inspired by linux_nat_thread_name.
	* nat/linux-procfs.h (linux_proc_tid_get_name): New declaration.
	* remote.c (struct private_thread_info) <name>: New field.
	(free_private_thread_info): Free name field.
	(remote_thread_name): New function.
	(thread_item_t) <name>: New field.
	(clear_threads_listing_context): Free name field.
	(start_thread): Get name xml attribute.
	(thread_attributes): Add "name" attribute.
	(remote_update_thread_list): Copy name field.
	(init_remote_ops): Assign remote_thread_name callback.
	* target.h (target_thread_name): Update comment.
	* NEWS: Mention remote thread name support.

gdb/gdbserver/ChangeLog:

	* linux-low.c (linux_target_ops): Use linux_proc_tid_get_name.
	* server.c (handle_qxfer_threads_worker): Refactor to include thread
	name in reply.
	* target.h (struct target_ops) <thread_name>: New field.
	(target_thread_name): New macro.

gdb/doc/ChangeLog:

	* gdb.texinfo (Thread List Format): Mention thread names.

1 files changed, 2 insertions, 2 deletions

diff --git a/gdb/target.h b/gdb/target.h
index ac28a41..65b717c 100644
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -1820,8 +1820,8 @@ extern char *normal_pid_to_str (ptid_t ptid);
 #define target_extra_thread_info(TP) \
      (current_target.to_extra_thread_info (&current_target, TP))
 
-/* Return the thread's name.  A NULL result means that the target
-   could not determine this thread's name.  */
+/* Return the thread's name, or NULL if the target is unable to determine it.
+   The returned value must not be freed by the caller.  */
 
 extern const char *target_thread_name (struct thread_info *);