vty: deprecate now empty node commands

Following I5021c64a787b63314e0f2f1cba0b8fc7bff4f09b a deprecation of
vty_install_default() and install_default() commands is indicated.

However, compiler warnings may clutter build output or even fail strict builds,
hence I am submitting the deprecation in a separate patch.

Depends: I5021c64a787b63314e0f2f1cba0b8fc7bff4f09b
Change-Id: Icf5d83f641e838cebcccc635a043e94ba352abff
diff --git a/include/osmocom/vty/command.h b/include/osmocom/vty/command.h
index 8fbdb7b..13d6e89 100644
--- a/include/osmocom/vty/command.h
+++ b/include/osmocom/vty/command.h
@@ -360,12 +360,12 @@
 
 /* Prototypes. */
 void install_node(struct cmd_node *, int (*)(struct vty *));
-void install_default(int node_type);
+void install_default(int node_type) OSMO_DEPRECATED("Now happens implicitly with install_node()");
 void install_element(int node_type, struct cmd_element *);
 void install_element_ve(struct cmd_element *cmd);
 void sort_node(void);
 
-void vty_install_default(int node_type);
+void vty_install_default(int node_type) OSMO_DEPRECATED("Now happens implicitly with install_node()");
 
 /* Concatenates argv[shift] through argv[argc-1] into a single NUL-terminated
    string with a space between each element (allocated using