Include system_error directly.

llvm-svn: 210802

clang/lib/Frontend/CompilerInvocation.cpp

@@ -33,10 +33,10 @@
 #include "llvm/Support/Host.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Process.h"
-#include "llvm/Support/system_error.h"
 #include <atomic>
 #include <memory>
 #include <sys/stat.h>
+#include <system_error>
 using namespace clang;
 
 //===----------------------------------------------------------------------===//