[CMake] Fix statically linking in libcxxabi if built separately

[mstorsjo]

Summary

In this case, CMake doesn't know about the c++abi target within the same CMake run.

This reverts this aspect back to how it was before SVN r357811.

lib/CMakeLists.txt

PROPERTIES
       SOVERSION     "${LIBCXX_ABI_VERSION}"
       DEFINE_SYMBOL ""
   )
   cxx_set_common_defines(cxx_shared)
 
   # Link against libc++abi
   if (LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY)
     if (APPLE)
-      target_link_libraries(cxx_shared PRIVATE "-Wl,-force_load" "$<TARGET_LINKER_FILE:${LIBCXX_CXX_STATIC_ABI_LIBRARY}>")
+      target_link_libraries(cxx_shared PRIVATE "-Wl,-force_load" "${LIBCXX_CXX_STATIC_ABI_LIBRARY}")
     else()
-      target_link_libraries(cxx_shared PRIVATE "-Wl,--whole-archive,-Bstatic" "$<TARGET_LINKER_FILE:${LIBCXX_CXX_STATIC_ABI_LIBRARY}>" "-Wl,-Bdynamic,--no-whole-archive")
+      target_link_libraries(cxx_shared PRIVATE "-Wl,--whole-archive,-Bstatic" "${LIBCXX_CXX_STATIC_ABI_LIBRARY}" "-Wl,-Bdynamic,--no-whole-archive")
     endif()
   else()
     target_link_libraries(cxx_shared PRIVATE "${LIBCXX_CXX_SHARED_ABI_LIBRARY}")
     list(APPEND LIBCXX_INTERFACE_LIBRARIES "${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