build: use correct libraries for clock_gettime

On OpenBSD, clock_gettime() exists in libc rather than librt, and
blindly linking with -lrt made the build fail.  Gnulib already
did the work for determining which libraries to use, so we should
reuse that work rather than doing it ourselves.

* bootstrap.conf (gnulib_modules): Pull in clock-time.
* configure.ac (RT_LIBS): Drop.
* src/Makefile.am (libvirt_util_la_LIBADD): Use gnulib variable
instead.
* src/util/virtime.c (includes): Simplify.

bootstrap.conf

@@ -30,6 +30,7 @@ c-strcasestr
 calloc-posix
 canonicalize-lgpl
 chown
+clock-time
 close
 connect
 configmake

configure.ac

@@ -183,16 +183,6 @@ LIBS="$LIBS $LIB_PTHREAD $LIBMULTITHREAD"
 AC_CHECK_FUNCS([pthread_mutexattr_init])
 LIBS=$old_libs
 
-old_LIBS=$LIBS
-RT_LIBS=
-LIBS="$LIBS $LIB_PTHREAD -lrt"
-AC_CHECK_FUNC([clock_gettime],[
-     AC_DEFINE([HAVE_CLOCK_GETTIME],[],[Defined if clock_gettime() exists in librt.so])
-     RT_LIBS=-lrt
-])
-LIBS=$old_libs
-AC_SUBST(RT_LIBS)
-
 dnl Availability of various common headers (non-fatal if missing).
 AC_CHECK_HEADERS([pwd.h paths.h regex.h sys/un.h \
   sys/poll.h syslog.h mntent.h net/ethernet.h linux/magic.h \

src/Makefile.am

@@ -668,7 +668,7 @@ libvirt_util_la_CFLAGS = $(CAPNG_CFLAGS) $(YAJL_CFLAGS) $(LIBNL_CFLAGS) \
 		$(DBUS_CFLAGS) $(LDEXP_LIBM)
 libvirt_util_la_LIBADD = $(CAPNG_LIBS) $(YAJL_LIBS) $(LIBNL_LIBS) \
 		$(THREAD_LIBS) $(AUDIT_LIBS) $(DEVMAPPER_LIBS) \
-		$(RT_LIBS) $(DBUS_LIBS) $(MSCOM_LIBS) $(LIBXML_LIBS)
+		$(LIB_CLOCK_GETTIME) $(DBUS_LIBS) $(MSCOM_LIBS) $(LIBXML_LIBS)
 
 
 noinst_LTLIBRARIES += libvirt_conf.la

src/util/virtime.c

@@ -1,7 +1,7 @@
 /*
  * virtime.c: Time handling functions
  *
- * Copyright (C) 2006-2011 Red Hat, Inc.
+ * Copyright (C) 2006-2012 Red Hat, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -34,9 +34,7 @@
 #include <config.h>
 
 #include <stdio.h>
-#ifndef HAVE_CLOCK_GETTIME
-# include <sys/time.h>
-#endif
+#include <sys/time.h>
 
 #include "virtime.h"
 #include "util.h"