[libc++] Use PRIVATE to link benchmark dependencies

It's better style to use PRIVATE when linking libraries to executables,
and it doesn't make a difference since executables don't need to propagate
their link-time dependencies anyway.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@374050 91177308-0d34-0410-b5e6-96231b3b80d8

Author: ldionne

benchmarks/CMakeLists.txt

@@ -135,16 +135,16 @@ function(add_benchmark_test name source_file)
   add_dependencies(${libcxx_target} cxx cxx-headers google-benchmark-libcxx)
   add_dependencies(cxx-benchmarks ${libcxx_target})
   if (LIBCXX_ENABLE_SHARED)
-    target_link_libraries(${libcxx_target} cxx_shared)
+    target_link_libraries(${libcxx_target} PRIVATE cxx_shared)
   else()
-    target_link_libraries(${libcxx_target} cxx_static)
+    target_link_libraries(${libcxx_target} PRIVATE cxx_static)
   endif()
   if (TARGET cxx_experimental)
-    target_link_libraries(${libcxx_target} cxx_experimental)
+    target_link_libraries(${libcxx_target} PRIVATE cxx_experimental)
   endif()
-  target_link_libraries(${libcxx_target} -lbenchmark)
+  target_link_libraries(${libcxx_target} PRIVATE -lbenchmark)
   if (LLVM_USE_SANITIZER)
-    target_link_libraries(${libcxx_target} -ldl)
+    target_link_libraries(${libcxx_target} PRIVATE -ldl)
   endif()
   set_target_properties(${libcxx_target}
     PROPERTIES
@@ -161,14 +161,14 @@ function(add_benchmark_test name source_file)
     add_executable(${native_target} EXCLUDE_FROM_ALL ${source_file})
     add_dependencies(${native_target} google-benchmark-native
                                       google-benchmark-libcxx)
-    target_link_libraries(${native_target} -lbenchmark)
+    target_link_libraries(${native_target} PRIVATE -lbenchmark)
     if (LIBCXX_BENCHMARK_NATIVE_STDLIB STREQUAL "libstdc++")
-      target_link_libraries(${native_target} ${LIBSTDCXX_FILESYSTEM_LIB})
+      target_link_libraries(${native_target} PRIVATE ${LIBSTDCXX_FILESYSTEM_LIB})
     elseif (LIBCXX_BENCHMARK_NATIVE_STDLIB STREQUAL "libc++")
-      target_link_libraries(${native_target} -lc++fs -lc++experimental)
+      target_link_libraries(${native_target} PRIVATE -lc++fs -lc++experimental)
     endif()
     if (LIBCXX_HAS_PTHREAD_LIB)
-      target_link_libraries(${native_target} -pthread)
+      target_link_libraries(${native_target} PRIVATE -pthread)
     endif()
     add_dependencies(cxx-benchmarks ${native_target})
     set_target_properties(${native_target}