add support for privilege separation

Privileged helper that will perform adjtime(), settimeofday(), bind() on
behalf of chronyd when running as non-root user.

privops.h

@@ -0,0 +1,54 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Bryan Christianson 2015
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  Perform privileged operations over a unix socket to a privileged fork.
+
+*/
+
+#ifndef GOT_PRIVOPS_H
+#define GOT_PRIVOPS_H
+
+#ifdef PRIVOPS_ADJUSTTIME
+int PRV_AdjustTime(const struct timeval *delta, struct timeval *olddelta);
+#else
+#define PRV_AdjustTime adjtime
+#endif
+
+#ifdef PRIVOPS_SETTIME
+int PRV_SetTime(const struct timeval *tp, const struct timezone *tzp);
+#else
+#define PRV_SetTime settimeofday
+#endif
+
+#ifdef PRIVOPS_BINDSOCKET
+int PRV_BindSocket(int sock, struct sockaddr *address, socklen_t address_len);
+#else
+#define PRV_BindSocket bind
+#endif
+
+#ifdef PRIVOPS_HELPER
+void PRV_Initialise(void);
+void PRV_Finalise(void);
+#endif
+
+#endif