Add missing prototype to a common header file.

Bug: https://bugs.gentoo.org/882157

diff --git a/X11/xmpdvmkpkg.h b/X11/xmpdvmkpkg.h
index abaaa47..fd6c6f5 100644
--- a/X11/xmpdvmkpkg.h
+++ b/X11/xmpdvmkpkg.h
@@ -76,6 +76,7 @@ extern Widget g_statusw;
 void spectowidgets(void);
 void widgetstospec(struct pdvspec_st *spec);
 int  cmpspecandwidgets(void);
+void statusmsg(char *fmt, ...);
 void xu_SetMainTitle(const char *newtitle, const char *newprefix
  , Widget topshell);
 
-- 
2.41.0