[libc++][CMake] Make sure the benchmarks link against libc++abi

The refactoring in r357811 made it so that we didn't add the ABI library
to the list of LIBCXX_LIBRARIES. As a result, benchmarks didn't link to
the ABI library and were missing symbols. This broke the build bots.

As a drive-by fix, we also provide the SHARED ABI library to the linker
script instead of the STATIC ABI library.

This couldn't be discovered on Apple platforms because libc++.dylib
re-exports libc++abi.dylib symbols there.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@357818 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
index c9d33e6..8825e62 100644
--- a/lib/CMakeLists.txt
+++ b/lib/CMakeLists.txt
@@ -180,7 +180,8 @@
     endif()
   else()
     target_link_libraries(cxx_shared PRIVATE "${LIBCXX_CXX_SHARED_ABI_LIBRARY}")
-    list(APPEND LIBCXX_INTERFACE_LIBRARIES "${LIBCXX_CXX_STATIC_ABI_LIBRARY}")
+    list(APPEND LIBCXX_INTERFACE_LIBRARIES "${LIBCXX_CXX_SHARED_ABI_LIBRARY}") # For the linker script
+    list(APPEND LIBCXX_LIBRARIES "${LIBCXX_CXX_SHARED_ABI_LIBRARY}") # For the benchmarks
   endif()
 
   # Maybe re-export symbols from libc++abi