Start cleanup of unique_ptr tests.

One of the last sections of tests that still fail in C++03 are the unique_ptr
tests. This patch begins cleaning up the tests and fixing C++03 failures.

The main changes of this patch:
  - The "Deleter" type in "deleter.h" tried to be "move-only" in C++03. However
    the move simulation no longer works (see "__rv"). "Deleter" is now copy
    constructible in C++03. However copying "Deleter" will "move" the test value
    instead of copying it.

  - Reduce the unique.ptr.single.ctor tests files from ~25 to 4. There is no
    reason the tests were split through so many files.

llvm-svn: 243730