Include system_error directly.

llvm-svn: 210802
diff --git a/clang/lib/Tooling/JSONCompilationDatabase.cpp b/clang/lib/Tooling/JSONCompilationDatabase.cpp
index d99d787..94fdb5f 100644
--- a/clang/lib/Tooling/JSONCompilationDatabase.cpp
+++ b/clang/lib/Tooling/JSONCompilationDatabase.cpp
@@ -17,7 +17,7 @@
 #include "clang/Tooling/Tooling.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/Path.h"
-#include "llvm/Support/system_error.h"
+#include <system_error>
 
 namespace clang {
 namespace tooling {