stabilize build system: depends, installer, boost/bdb fixes, cross targets groundwork

depends/x86_64-pc-linux-gnu/include/boost/compute/async/wait_guard.hpp

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+//---------------------------------------------------------------------------//
+// Copyright (c) 2013-2015 Kyle Lutz <kyle.r.lutz@gmail.com>
+//
+// 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
+//
+// See http://boostorg.github.com/compute for more information.
+//---------------------------------------------------------------------------//
+
+#ifndef BOOST_COMPUTE_ASYNC_WAIT_GUARD_HPP
+#define BOOST_COMPUTE_ASYNC_WAIT_GUARD_HPP
+
+#include <boost/noncopyable.hpp>
+
+namespace boost {
+namespace compute {
+
+/// \class wait_guard
+/// \brief A guard object for synchronizing an operation on the device
+///
+/// The wait_guard class stores a waitable object representing an operation
+/// on a compute device (e.g. \ref event, \ref future "future<T>") and calls
+/// its \c wait() method when the guard object goes out of scope.
+///
+/// This is useful for ensuring that an OpenCL operation completes before
+/// leaving the current scope and cleaning up any resources.
+///
+/// For example:
+/// \code
+/// // enqueue a compute kernel for execution
+/// event e = queue.enqueue_nd_range_kernel(...);
+///
+/// // call e.wait() upon exiting the current scope
+/// wait_guard<event> guard(e);
+/// \endcode
+///
+/// \ref wait_list, wait_for_all()
+template<class Waitable>
+class wait_guard : boost::noncopyable
+{
+public:
+    /// Creates a new wait_guard object for \p waitable.
+    wait_guard(const Waitable &waitable)
+        : m_waitable(waitable)
+    {
+    }
+
+    /// Destroys the wait_guard object. The default implementation will call
+    /// \c wait() on the stored waitable object.
+    ~wait_guard()
+    {
+        m_waitable.wait();
+    }
+
+private:
+    Waitable m_waitable;
+};
+
+} // end compute namespace
+} // end boost namespace
+
+#endif // BOOST_COMPUTE_ASYNC_WAIT_GUARD_HPP