[libcxx] Remove unused definition of aligned allocation macro on old OS X

We don't support mac OS 10.6 and older anymore, so this macro can never
be defined. This bit of code had been added in D28931 as a fix for
PR31448, but it doesn't seem necessary anymore.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@347427 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed