[libc++] Revert to using PUBLIC instead of PRIVATE when linking system libs

It turns out the benchmarks need to link against those libraries
explicitly too, so CMake's propagation of PUBLIC dependencies is
used.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@373506 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 426f7a6..93be30b 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -143,40 +143,40 @@
   target_add_link_flags_if_supported(${target} PRIVATE "/nodefaultlib")
 
   if (LIBCXX_HAS_SYSTEM_LIB)
-    target_link_libraries(${target} PRIVATE System)
+    target_link_libraries(${target} PUBLIC System)
   endif()
 
   if (LIBCXX_HAS_PTHREAD_LIB)
-    target_link_libraries(${target} PRIVATE pthread)
+    target_link_libraries(${target} PUBLIC pthread)
   endif()
 
   if (LIBCXX_HAS_C_LIB)
-    target_link_libraries(${target} PRIVATE c)
+    target_link_libraries(${target} PUBLIC c)
   endif()
 
   if (LIBCXX_HAS_M_LIB)
-    target_link_libraries(${target} PRIVATE m)
+    target_link_libraries(${target} PUBLIC m)
   endif()
 
   if (LIBCXX_HAS_RT_LIB)
-    target_link_libraries(${target} PRIVATE rt)
+    target_link_libraries(${target} PUBLIC rt)
   endif()
 
   if (LIBCXX_USE_COMPILER_RT)
     find_compiler_rt_library(builtins LIBCXX_BUILTINS_LIBRARY)
     if (LIBCXX_BUILTINS_LIBRARY)
-      target_link_libraries(${target} PRIVATE "${LIBCXX_BUILTINS_LIBRARY}")
+      target_link_libraries(${target} PUBLIC "${LIBCXX_BUILTINS_LIBRARY}")
     endif()
   elseif (LIBCXX_HAS_GCC_S_LIB)
-    target_link_libraries(${target} PRIVATE gcc_s)
+    target_link_libraries(${target} PUBLIC gcc_s)
   endif()
 
   if (LIBCXX_HAVE_CXX_ATOMICS_WITH_LIB)
-    target_link_libraries(${target} PRIVATE atomic)
+    target_link_libraries(${target} PUBLIC atomic)
   endif()
 
   if (MINGW)
-    target_link_libraries(${target} PRIVATE "${MINGW_LIBRARIES}")
+    target_link_libraries(${target} PUBLIC "${MINGW_LIBRARIES}")
   endif()
 
   if (LIBCXX_TARGETING_MSVC)
@@ -186,13 +186,13 @@
       set(LIB_SUFFIX "")
     endif()
 
-    target_link_libraries(${target} PRIVATE ucrt${LIB_SUFFIX}) # Universal C runtime
-    target_link_libraries(${target} PRIVATE vcruntime${LIB_SUFFIX}) # C++ runtime
-    target_link_libraries(${target} PRIVATE msvcrt${LIB_SUFFIX}) # C runtime startup files
-    target_link_libraries(${target} PRIVATE msvcprt${LIB_SUFFIX}) # C++ standard library. Required for exception_ptr internals.
+    target_link_libraries(${target} PUBLIC ucrt${LIB_SUFFIX}) # Universal C runtime
+    target_link_libraries(${target} PUBLIC vcruntime${LIB_SUFFIX}) # C++ runtime
+    target_link_libraries(${target} PUBLIC msvcrt${LIB_SUFFIX}) # C runtime startup files
+    target_link_libraries(${target} PUBLIC msvcprt${LIB_SUFFIX}) # C++ standard library. Required for exception_ptr internals.
     # Required for standards-complaint wide character formatting functions
     # (e.g. `printfw`/`scanfw`)
-    target_link_libraries(${target} PRIVATE iso_stdio_wide_specifiers)
+    target_link_libraries(${target} PUBLIC iso_stdio_wide_specifiers)
   endif()
 endfunction()