Don't use 'using std::error_code' in include/llvm.

This should make sure that most new uses use the std prefix.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210835 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/LockFileManager.h

@@ -16,7 +16,6 @@
 #include <utility> // for std::pair
 
 namespace llvm {
-using std::error_code;
 /// \brief Class that manages the creation of a lock file to aid
 /// implicit coordination between different processes.
 ///
@@ -56,7 +55,7 @@ private:
   SmallString<128> UniqueLockFileName;
 
   Optional<std::pair<std::string, int> > Owner;
-  Optional<error_code> Error;
+  Optional<std::error_code> Error;
 
   LockFileManager(const LockFileManager &) LLVM_DELETED_FUNCTION;
   LockFileManager &operator=(const LockFileManager &) LLVM_DELETED_FUNCTION;