Remove 'using std::errro_code' from lib.

llvm-svn: 210871
diff --git a/llvm/lib/IR/Core.cpp b/llvm/lib/IR/Core.cpp
index 5dfe9a6..197b6cb 100644
--- a/llvm/lib/IR/Core.cpp
+++ b/llvm/lib/IR/Core.cpp
@@ -41,7 +41,6 @@
 #include <system_error>
 
 using namespace llvm;
-using std::error_code;
 
 #define DEBUG_TYPE "ir"
 
@@ -2602,7 +2601,7 @@
     char **OutMessage) {
 
   std::unique_ptr<MemoryBuffer> MB;
-  error_code ec;
+  std::error_code ec;
   if (!(ec = MemoryBuffer::getFile(Path, MB))) {
     *OutMemBuf = wrap(MB.release());
     return 0;
@@ -2615,7 +2614,7 @@
 LLVMBool LLVMCreateMemoryBufferWithSTDIN(LLVMMemoryBufferRef *OutMemBuf,
                                          char **OutMessage) {
   std::unique_ptr<MemoryBuffer> MB;
-  error_code ec;
+  std::error_code ec;
   if (!(ec = MemoryBuffer::getSTDIN(MB))) {
     *OutMemBuf = wrap(MB.release());
     return 0;