The move / swap members were not correctly taking all of the possible states of the basic_stringbuf into account.  Just rewrote these members.  Test included.  This fixes http://llvm.org/bugs/show_bug.cgi?id=15659.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@178690 91177308-0d34-0410-b5e6-96231b3b80d8
Fix stupid but harmless type-o.  Fixes http://llvm.org/bugs/show_bug.cgi?id=15657.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@178691 91177308-0d34-0410-b5e6-96231b3b80d8
Somehow search_n never got tested, so of course it had a bug in it.  This fixes http://llvm.org/bugs/show_bug.cgi?id=15667.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@178764 91177308-0d34-0410-b5e6-96231b3b80d8
More work on debug mode for list.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@178819 91177308-0d34-0410-b5e6-96231b3b80d8
More list debug mode tests.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@178873 91177308-0d34-0410-b5e6-96231b3b80d8
Fix bug in __libcpp_db::__iterator_copy.  Add debug test for swaping lists.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@178892 91177308-0d34-0410-b5e6-96231b3b80d8