Make the C++HL Pool class & co. explicitly non-copyable.

* subversion/bindings/cxxhl/include/svncxxhl/_compat.hpp
  (compat::noncopyable): Define mixin, or use Boost's version if available.

* subversion/bindings/cxxhl/src/aprwrap/pool.hpp
  (Pool, Pool::Iteration, IterationPool): Derive from non-copyable.
  (Pool::Pool, IterationPool::IterationPool): Change subpool constructors to
   accept a pointer to the parent instead of a reference, to make them
   obviously different from copy constructors.

* subversion/bindings/cxxhl/tests/test_aprwrap.cpp (CreateSubpool):
   Update for changed subpool constructor signature.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1507574 13f79535-47bb-0310-9956-ffa450edef68