Fix support for systems without ntptimeval (bug #50433, http://bugs.ntp.org/979)

Index: ntp-4.2.2+dfsg/include/ntp_syscall.h
===================================================================
--- ntp-4.2.2+dfsg.orig/include/ntp_syscall.h	2004-02-25 05:57:56.000000000 +0000
+++ ntp-4.2.2+dfsg/include/ntp_syscall.h	2006-07-02 14:25:13.000000000 +0000
@@ -24,6 +24,15 @@
 
 #  define ntp_adjtime(t)	__adjtimex((t))
 
+#ifndef HAVE_STRUCT_NTPTIMEVAL
+struct ntptimeval
+{
+  struct timeval time;  /* current time (ro) */
+  long int maxerror;    /* maximum error (us) (ro) */
+  long int esterror;    /* estimated error (us) (ro) */
+};
+#endif
+
 static inline int
 ntp_gettime(
 	struct ntptimeval *ntv