Update clang to r339409.

Change-Id: I800772d2d838223be1f6b40d490c4591b937fca2
diff --git a/linux-x64/clang/lib64/cmake/llvm/LLVM-Config.cmake b/linux-x64/clang/lib64/cmake/llvm/LLVM-Config.cmake
index 10fd526..8eabddc 100644
--- a/linux-x64/clang/lib64/cmake/llvm/LLVM-Config.cmake
+++ b/linux-x64/clang/lib64/cmake/llvm/LLVM-Config.cmake
@@ -68,7 +68,7 @@
   cmake_parse_arguments(ARG "USE_SHARED" "" "" ${ARGN})
   set(link_components ${ARG_UNPARSED_ARGUMENTS})
 
-  if(USE_SHARED)
+  if(ARG_USE_SHARED)
     # If USE_SHARED is specified, then we link against libLLVM,
     # but also against the component libraries below. This is
     # done in case libLLVM does not contain all of the components