[libgtop] Explain why we undef STAT_STATVFS on OpenBSD

[Jasper Lievisse Adriaanse <jasperla src gnome org>]

commit 62239cfe50e7f453300e95124234a61a1f86adf7
Author: Jasper Lievisse Adriaanse <jasper humppa nl>
Date:   Thu Jun 16 13:14:22 2011 +0200

    Explain why we undef STAT_STATVFS on OpenBSD

 sysdeps/openbsd/fsusage.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/sysdeps/openbsd/fsusage.c b/sysdeps/openbsd/fsusage.c
index 5ffc433..9015f9f 100644
--- a/sysdeps/openbsd/fsusage.c
+++ b/sysdeps/openbsd/fsusage.c
@@ -2,6 +2,11 @@
 
 #include <config.h>
 
+/*
+ * statvfs is lacking various members which are present in statfs,
+ * like f_(a)syncreads and f_(a)syncwrites. So eventhough we have
+ * statvfs, undef it here untill those members are added.
+ */
 #undef HAVE_SYS_STATVFS_H
 #undef STAT_STATVFS