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

depends/x86_64-pc-linux-gnu/include/boost/process/shell.hpp

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+// Copyright (c) 2006, 2007 Julio M. Merino Vidal
+// Copyright (c) 2008 Ilya Sokolov, Boris Schaeling
+// Copyright (c) 2009 Boris Schaeling
+// Copyright (c) 2010 Felipe Tanus, Boris Schaeling
+// Copyright (c) 2011, 2012 Jeff Flinn, Boris Schaeling
+// Copyright (c) 2016 Klemens D. Morgenstern
+//
+// 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)
+
+#ifndef BOOST_PROCESS_SHELL_PATH_HPP
+#define BOOST_PROCESS_SHELL_PATH_HPP
+
+#include <boost/process/detail/config.hpp>
+#include <boost/process/detail/traits/wchar_t.hpp>
+
+#if defined(BOOST_POSIX_API)
+#include <boost/process/detail/posix/shell_path.hpp>
+#elif defined(BOOST_WINDOWS_API)
+#include <boost/process/detail/windows/shell_path.hpp>
+#endif
+
+/** \file boost/process/shell.hpp
+ *
+ *    Header which provides the shell property. This provides the
+ *    property to launch a process through the system shell.
+ *    It also allows the user to obtain the shell-path via shell().
+\xmlonly
+<programlisting>
+namespace boost {
+  namespace process {
+    <emphasis>unspecified</emphasis> <globalname alt="boost::process::shell">shell</globalname>;
+  }
+}
+</programlisting>
+\endxmlonly
+
+ */
+
+namespace boost { namespace process { namespace detail {
+
+
+struct shell_
+{
+    constexpr shell_() {}
+
+    boost::filesystem::path operator()() const
+    {
+        return boost::process::detail::api::shell_path();
+    }
+    boost::filesystem::path operator()(std::error_code & ec) const noexcept
+    {
+        return boost::process::detail::api::shell_path(ec);
+    }
+};
+
+template<>
+struct is_wchar_t<shell_> : is_wchar_t<boost::filesystem::path>
+{
+};
+
+}
+/**
+The shell property enables to launch a program through the shell of the system.
+
+\code{.cpp}
+system("gcc", shell);
+\endcode
+
+The shell argument goes without any expression. The operator() is overloaded, to
+obtain the path of the system shell.
+
+\code{.cpp}
+auto shell_cmd = shell();
+//avoid exceptions
+std::error_code ec;
+shell_cmd = shell(ec);
+\endcode
+
+\attention Launching through the shell will NOT provide proper error handling, i.e.
+you will get an error via the return code.
+
+\attention Executing shell commands that incorporate unsanitized input from an untrusted source makes a program vulnerable to shell injection, a serious security flaw which can result in arbitrary command execution. For this reason, the use of `shell` is strongly discouraged in cases where the command string is constructed from external input:
+
+*/
+constexpr ::boost::process::detail::shell_ shell;
+
+}}
+
+
+
+#endif