[libc++] NFC: Move unused include of <limits> to allocator_traits.h

The include should have been moved when I split allocator_traits.h out
of memory.

GitOrigin-RevId: b12539225930dd2738a79ac9eec455e63413ab91
diff --git a/include/__memory/allocator_traits.h b/include/__memory/allocator_traits.h
index 9443f61..be44535 100644
--- a/include/__memory/allocator_traits.h
+++ b/include/__memory/allocator_traits.h
@@ -13,6 +13,7 @@
 #include <__config>
 #include <__memory/base.h>
 #include <__memory/pointer_traits.h>
+#include <limits>
 #include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/include/memory b/include/memory
index d326476..852824f 100644
--- a/include/memory
+++ b/include/memory
@@ -673,7 +673,6 @@
 #include <cstdint>
 #include <new>
 #include <utility>
-#include <limits>
 #include <iterator>
 #include <__functional_base>
 #include <iosfwd>