Found six (nmostly) identical files named 'test_allocator.h' in the libcxx test suite. Moved one to /support, made it a superset, and removed all but one of the others, and iupdated all the includes. Left the odd one (thread/futures/test_allocator.h) for later.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@196174 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/containers/sequences/list/list.special/swap_noexcept.pass.cpp b/test/containers/sequences/list/list.special/swap_noexcept.pass.cpp
index f2d6cc1..7a23398 100644
--- a/test/containers/sequences/list/list.special/swap_noexcept.pass.cpp
+++ b/test/containers/sequences/list/list.special/swap_noexcept.pass.cpp
@@ -19,7 +19,7 @@
 #include <cassert>
 
 #include "../../../MoveOnly.h"
-#include "../../../test_allocator.h"
+#include "test_allocator.h"
 
 template <class T>
 struct some_alloc