lib: add api method to read current config path

Signed-off-by: Christian Franke <chris@opensourcerouting.org>
diff --git a/lib/command.h b/lib/command.h
index 6a20e23..09bc516 100644
--- a/lib/command.h
+++ b/lib/command.h
@@ -556,7 +556,7 @@
 extern struct cmd_element config_quit_cmd;
 extern struct cmd_element config_help_cmd;
 extern struct cmd_element config_list_cmd;
-extern char *host_config_file (void);
+extern const char *host_config_get (void);
 extern void host_config_set (char *);
 
 extern void print_version (const char *);