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

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

llvm-svn: 210835
diff --git a/llvm/tools/bugpoint/ExtractFunction.cpp b/llvm/tools/bugpoint/ExtractFunction.cpp
index 38cdf24..a257840 100644
--- a/llvm/tools/bugpoint/ExtractFunction.cpp
+++ b/llvm/tools/bugpoint/ExtractFunction.cpp
@@ -33,6 +33,7 @@
 #include "llvm/Transforms/Utils/CodeExtractor.h"
 #include <set>
 using namespace llvm;
+using std::error_code;
 
 #define DEBUG_TYPE "bugpoint"