gdb: make add_com_alias accept target as a cmd_list_element

The alias creation functions currently accept a name to specify the
target command.  They pass this to add_alias_cmd, which needs to lookup
the target command by name.

Given that:

 - We don't support creating an alias for a command before that command
   exists.
 - We always use add_info_alias just after creating that target command,
   and therefore have access to the target command's cmd_list_element.

... change add_com_alias to accept the target command as a
cmd_list_element (other functions are done in subsequent patches).  This
ensures we don't create the alias before the target command, because you
need to get the cmd_list_element from somewhere when you call the alias
creation function.  And it avoids an unecessary command lookup.  So it
seems better to me in every aspect.

gdb/ChangeLog:

	* command.h (add_com_alias): Accept target as
	cmd_list_element.  Update callers.

Change-Id: I24bed7da57221cc77606034de3023fedac015150

1 files changed, 4 insertions, 3 deletions

diff --git a/gdb/record.c b/gdb/record.c
index 7dae18f..a09137b 100644
--- a/gdb/record.c
+++ b/gdb/record.c
@@ -785,12 +785,13 @@ A size of \"unlimited\" means unlimited lines.  The default is 10."),
 			    set_record_call_history_size, NULL,
 			    &set_record_cmdlist, &show_record_cmdlist);
 
-  c = add_prefix_cmd ("record", class_obscure, cmd_record_start,
+  cmd_list_element *record_cmd
+    = add_prefix_cmd ("record", class_obscure, cmd_record_start,
 		      _("Start recording."),
 		      &record_cmdlist, 0, &cmdlist);
-  set_cmd_completer (c, filename_completer);
+  set_cmd_completer (record_cmd, filename_completer);
 
-  add_com_alias ("rec", "record", class_obscure, 1);
+  add_com_alias ("rec", record_cmd, class_obscure, 1);
   add_basic_prefix_cmd ("record", class_support,
 			_("Set record options."), &set_record_cmdlist,
 			0, &setlist);