[CMake] Enable libc++ for Fuchsia toolchain on Darwin

This is necessary in order to get a working C++ compiler on Darwin
since Clang expects libc++ headers to be part of the toolchain.

Differential Revision: https://reviews.llvm.org/D46075

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@330855 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/cmake/caches/Fuchsia-stage2.cmake b/cmake/caches/Fuchsia-stage2.cmake
index 6b93e15..39c1b40 100644
--- a/cmake/caches/Fuchsia-stage2.cmake
+++ b/cmake/caches/Fuchsia-stage2.cmake
@@ -38,16 +38,7 @@
 set(LLVM_RUNTIME_TARGETS "default;x86_64-fuchsia;aarch64-fuchsia;x86_64-fuchsia-asan:x86_64-fuchsia;aarch64-fuchsia-asan:aarch64-fuchsia" CACHE STRING "")
 
 # Set the default target runtimes options.
-if(APPLE)
-  # Disable installing libc++, libc++abi or libunwind on Darwin, since Clang
-  # driver doesn't know how to use libraries that are part of the toolchain.
-  set(LIBUNWIND_INSTALL_HEADERS OFF CACHE BOOL "")
-  set(LIBUNWIND_INSTALL_LIBRARY OFF CACHE BOOL "")
-  set(LIBCXXABI_INSTALL_HEADERS OFF CACHE BOOL "")
-  set(LIBCXXABI_INSTALL_LIBRARY OFF CACHE BOOL "")
-  set(LIBCXX_INSTALL_HEADERS OFF CACHE BOOL "")
-  set(LIBCXX_INSTALL_LIBRARY OFF CACHE BOOL "")
-else()
+if(NOT APPLE)
   set(LIBUNWIND_ENABLE_SHARED OFF CACHE BOOL "")
   set(LIBUNWIND_USE_COMPILER_RT ON CACHE BOOL "")
   set(LIBUNWIND_INSTALL_LIBRARY OFF CACHE BOOL "")