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
3 files changed