vty: Implement missing public API host_config_file()
The API was defined in the header file but not implemented.
Change-Id: I69de9864fa7cd421557b9fc630beefea6d90b4cc
diff --git a/include/osmocom/vty/command.h b/include/osmocom/vty/command.h
index 228dc5b..81333b4 100644
--- a/include/osmocom/vty/command.h
+++ b/include/osmocom/vty/command.h
@@ -457,7 +457,7 @@
extern struct cmd_element config_help_cmd;
extern struct cmd_element config_list_cmd;
extern struct cmd_element config_end_cmd;
-char *host_config_file();
+const char *host_config_file(void);
void host_config_set(const char *);
char *osmo_asciidoc_escape(const char *inp);