fix timer_manager to really use a steady clock when needed

This is a bit of a hack, since up to boost version 1.61 the time of the steady clock is always converted to system clock,
which is then used for the wait... which obviously doesn't help if we explicitly want the steady clock.

So as a workaround, include the backported versions of the boost condition variable if boost version is not recent enough.

clients/roscpp/CMakeLists.txt

@@ -22,7 +22,7 @@ list(GET roscpp_VERSION_LIST 2 roscpp_VERSION_PATCH)
 
 configure_file(${CMAKE_CURRENT_SOURCE_DIR}/include/ros/common.h.in ${CATKIN_DEVEL_PREFIX}/${CATKIN_GLOBAL_INCLUDE_DESTINATION}/ros/common.h)
 
-find_package(Boost REQUIRED COMPONENTS signals filesystem system)
+find_package(Boost REQUIRED COMPONENTS signals filesystem system chrono)
 
 include_directories(include ${CATKIN_DEVEL_PREFIX}/${CATKIN_GLOBAL_INCLUDE_DESTINATION}/ros ${catkin_INCLUDE_DIRS} ${Boost_INCLUDE_DIRS})
 

clients/roscpp/include/boost_161_condition_variable.h

@@ -0,0 +1,23 @@
+#ifndef BOOST_THREAD_CONDITION_VARIABLE_HPP
+#define BOOST_THREAD_CONDITION_VARIABLE_HPP
+
+//  condition_variable.hpp
+//
+//  (C) Copyright 2007 Anthony Williams
+//
+//  Distributed under the Boost Software License, Version 1.0. (See
+//  accompanying file LICENSE_1_0.txt or copy at
+//  http://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/thread/detail/platform.hpp>
+#if defined(BOOST_THREAD_PLATFORM_WIN32)
+#include <boost/thread/win32/condition_variable.hpp>
+#elif defined(BOOST_THREAD_PLATFORM_PTHREAD)
+//#include <boost/thread/pthread/condition_variable.hpp>
+#include "boost_161_pthread_condition_variable.h"
+#else
+#error "Boost threads unavailable on this platform"
+#endif
+
+#endif
+