[gnome-settings-daemon] [sound] Add missing include for OpenBSD

[Jens Granseuer <jensg src gnome org>]

commit a1336c0a10fc9a9c5fc181a871da1b865f15dd52
Author: Jasper Lievisse Adriaanse <jasper humppa nl>
Date:   Mon Nov 16 19:42:54 2009 +0100

    [sound] Add missing include for OpenBSD
    
    Part of bug #598573.

 plugins/sound/gsd-sound-manager.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/plugins/sound/gsd-sound-manager.c b/plugins/sound/gsd-sound-manager.c
index fab5531..e773fcf 100644
--- a/plugins/sound/gsd-sound-manager.c
+++ b/plugins/sound/gsd-sound-manager.c
@@ -27,6 +27,7 @@
 #include <unistd.h>
 #include <string.h>
 #include <errno.h>
+#include <signal.h>
 
 #include <locale.h>