Merge branch 'clang-c++11-bdlib'

* clang-c++11-bdlib:
  Update ax_cxx_compile_stdcxx_11 from upstream 3cb2915
  bdlib update
  Only prefer clang after usable C++11 compilers
  Update bdlib for C++11 usage
  Require C++11
  Fix fatal clang error due to ERR_get_error returning unsigned
  Prefer clang++

Conflicts:
	lib/bdlib
Merge branch 'master' into next

* master:

Conflicts:
	doc/UPDATES