[libcxx] Add support for linking libc++ against a static ABI library.

Summary:
This patch add the CMake option `LIBCXX_ENABLE_STATIC_ABI_LIBRARY` which, when enabled, will link libc++ against the static version of the ABI library.


Reviewers: mclow.lists, jroelofs, danalbert

Reviewed By: danalbert

Subscribers: compnerd, cfe-commits

Differential Revision: http://reviews.llvm.org/D8017

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@231076 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed