Update clang to r339409.

Change-Id: I800772d2d838223be1f6b40d490c4591b937fca2
diff --git a/linux-x64/clang/include/llvm/Support/Errc.h b/linux-x64/clang/include/llvm/Support/Errc.h
index 80bfe2a..dce4278 100644
--- a/linux-x64/clang/include/llvm/Support/Errc.h
+++ b/linux-x64/clang/include/llvm/Support/Errc.h
@@ -63,6 +63,7 @@
   no_such_process = int(std::errc::no_such_process),
   not_a_directory = int(std::errc::not_a_directory),
   not_enough_memory = int(std::errc::not_enough_memory),
+  not_supported = int(std::errc::not_supported),
   operation_not_permitted = int(std::errc::operation_not_permitted),
   permission_denied = int(std::errc::permission_denied),
   read_only_file_system = int(std::errc::read_only_file_system),