[cmake] [libcxx] Call llvm_setup_rpath() when adding shared libraries.

Clang and llvm already use llvm_setup_rpath(), so this change will
help standarize rpath usage across all projects.

Differential Revision: https://reviews.llvm.org/D42459

llvm-svn: 323453

libcxx/lib/CMakeLists.txt

@@ -222,6 +222,7 @@ set(LIBCXX_TARGETS)
 # Build the shared library.
 if (LIBCXX_ENABLE_SHARED)
   add_library(cxx_shared SHARED $<TARGET_OBJECTS:cxx_objects>)
+  llvm_setup_rpath(cxx_shared)
   target_link_libraries(cxx_shared ${LIBCXX_LIBRARIES})
   set_target_properties(cxx_shared
     PROPERTIES