[PATCH] D39888: [lsan] Only use VM_MEMORY_OS_ALLOC_ONCE on Darwin versions that support it

[Kostya Serebryany via Phabricator via llvm-commits]

kcc added a comment.

In https://reviews.llvm.org/D39888#924537, @dberris wrote:

> If I understand correctly, the check should happen at CMake configuration time, so that lsan doesn't even build for versions of OS X that aren't even supported.


I highly prefer conditionals in the code (*platform.h header) as opposed to cmake. 
Kuba, any idea how to guard against old versions of darwin?


https://reviews.llvm.org/D39888