Unify gdb puts functions

Now that filtered and unfiltered output can be treated identically, we
can unify the puts family of functions.  This is done under the name
"gdb_puts".  Most of this patch was written by script.

gdb/linux-thread-db.c

@@ -778,7 +778,7 @@ check_thread_db (struct thread_db_info *info, bool log_progress)
   catch (const gdb_exception_error &except)
     {
       if (warning_pre_print)
-	fputs_unfiltered (warning_pre_print, gdb_stderr);
+	gdb_puts (warning_pre_print, gdb_stderr);
 
       exception_fprintf (gdb_stderr, except,
 			 _("libthread_db integrity checks failed: "));