Disable aligned new/delete on Apple platforms without posix_memalign

Summary:
This patch disables the aligned new/delet overloads on Apple platforms without `posix_memalign`. This fixes libc++.dylib build regressions on such platforms.
This fixes http://llvm.org/PR31448.

This patch should also be merged into the 4.0 release branch


Reviewers: mclow.lists, rsmith, dexonsmith, jeremyhu

Reviewed By: mclow.lists

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D28931

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@292564 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/new b/include/new
index 6589f16..6e43501 100644
--- a/include/new
+++ b/include/new
@@ -101,8 +101,9 @@
 # define _LIBCPP_HAS_NO_SIZED_DEALLOCATION
 #endif
 
-#if !(defined(_LIBCPP_BUILDING_NEW) || _LIBCPP_STD_VER > 14 || \
-    (defined(__cpp_aligned_new) && __cpp_aligned_new >= 201606))
+#if !defined(_LIBCPP_HAS_NO_ALIGNED_ALLOCATION) && \
+    (!(defined(_LIBCPP_BUILDING_NEW) || _LIBCPP_STD_VER > 14 || \
+    (defined(__cpp_aligned_new) && __cpp_aligned_new >= 201606)))
 # define _LIBCPP_HAS_NO_ALIGNED_ALLOCATION
 #endif