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

llvm-svn: 292564
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: efea04512c28e1b8dea3d732e18a9213f3ed33c6
diff --git a/src/new.cpp b/src/new.cpp
index 391718f..b1e8ee3 100644
--- a/src/new.cpp
+++ b/src/new.cpp
@@ -151,6 +151,8 @@
     ::operator delete[](ptr);
 }
 
+#if !defined(_LIBCPP_HAS_NO_ALIGNED_ALLOCATION)
+
 _LIBCPP_WEAK
 void *
 operator new(std::size_t size, std::align_val_t alignment) _THROW_BAD_ALLOC
@@ -275,6 +277,8 @@
     ::operator delete[](ptr, alignment);
 }
 
+#endif // !defined(_LIBCPP_HAS_NO_ALIGNED_ALLOCATION)
+
 #endif // !__GLIBCXX__
 
 namespace std