Merge some detail changes.

- [53670] Avoid C style casts.
 - [55604] Fix #3346 boost/detail/scoped_enum_emulation.hpp enum_t conflict
   with Unix rpc/types.h
 - Don't foward declare containers when using gcc's parallel library and add a
   macro to disable forward declaration. Fixes #3866.


[SVN r59679]

test/Jamfile.v2

@@ -47,6 +47,7 @@ test-suite functional/hash
             :   <toolset>gcc:<define>_GLIBCXX_DEBUG
                 <toolset>darwin:<define>_GLIBCXX_DEBUG
             :   container_fwd_gcc_debug ]
+        [ run container_no_fwd_test.cpp ]
         [ compile-fail hash_no_ext_fail_test.cpp ]
         [ compile-fail namespace_fail_test.cpp ]
         [ run hash_no_ext_macro_1.cpp ]

test/container_no_fwd_test.cpp

@@ -0,0 +1,14 @@
+
+// Copyright 2010 Daniel James.
+// 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)
+
+#define BOOST_DETAIL_NO_CONTAINER_FWD
+
+#include <boost/detail/container_fwd.hpp>
+
+int main()
+{
+    std::set<int> x;
+    std::vector<std::string> y;
+}