record: fix typo in "set record" output

Alan Hayward pointed out a typo in the output of "set record btrace" that
I took from "set record".  Fix the original.

gdb/
	* record.c (set_record_command): Fix typo in message.

gdb/ChangeLog

@@ -1,3 +1,7 @@
+2018-04-13  Markus Metzger  <markus.t.metzger@intel.com>
+
+	* record.c (set_record_command): Fix typo in message.
+
 2018-04-13  Markus Metzger  <markus.t.metzger@intel.com>
 
 	* record-btrace.c (cmd_set_record_btrace): Print sub-commands.

gdb/record.c

@@ -320,7 +320,7 @@ static void
 set_record_command (const char *args, int from_tty)
 {
   printf_unfiltered (_("\"set record\" must be followed "
-		       "by an apporpriate subcommand.\n"));
+		       "by an appropriate subcommand.\n"));
   help_list (set_record_cmdlist, "set record ", all_commands, gdb_stdout);
 }