include system_error directly.

llvm-svn: 210801
diff --git a/lld/lib/ReaderWriter/MachO/MachONormalizedFileFromAtoms.cpp b/lld/lib/ReaderWriter/MachO/MachONormalizedFileFromAtoms.cpp
index 5463f77..e441b9b 100644
--- a/lld/lib/ReaderWriter/MachO/MachONormalizedFileFromAtoms.cpp
+++ b/lld/lib/ReaderWriter/MachO/MachONormalizedFileFromAtoms.cpp
@@ -32,8 +32,8 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/MachO.h"
-#include "llvm/Support/system_error.h"
 #include <map>
+#include <system_error>
 
 using llvm::StringRef;
 using llvm::isa;