Use daemon(3) function where available.

svn:r665

configure.in

@@ -136,7 +136,7 @@ dnl These headers are not essential
 
 AC_CHECK_HEADERS(stdint.h sys/types.h inttypes.h sys/wait.h netinet/in.h arpa/inet.h)
 
-AC_CHECK_FUNCS(gettimeofday ftime socketpair uname)
+AC_CHECK_FUNCS(gettimeofday ftime socketpair uname daemon)
 
 dnl In case we aren't given a working stdint.h, we'll need to grow our own.
 dnl Watch out.

src/common/util.c

@@ -548,7 +548,13 @@ get_uname(void)
 }
       
 void daemonize(void) {
-#ifndef MS_WINDOWS
+#ifdef HAVE_DAEMON
+  if (daemon(0 /* chdir to / */,
+	     0 /* Redirect std* to /dev/null */)) {
+    log_fn(LOG_ERR, "Daemon returned an error: %s", strerror(errno));
+    exit(1);
+  }
+#elif ! defined(MS_WINDOWS)
   /* Fork; parent exits. */
   if (fork())
     exit(0);