Remove 'using std::errro_code' from lib.

llvm-svn: 210871
diff --git a/llvm/lib/Support/FileUtilities.cpp b/llvm/lib/Support/FileUtilities.cpp
index 729e447..0d26baf 100644
--- a/llvm/lib/Support/FileUtilities.cpp
+++ b/llvm/lib/Support/FileUtilities.cpp
@@ -22,7 +22,6 @@
 #include <cstring>
 #include <system_error>
 using namespace llvm;
-using std::error_code;
 
 static bool isSignedChar(char C) {
   return (C == '+' || C == '-');
@@ -178,13 +177,13 @@
   // Now its safe to mmap the files into memory because both files
   // have a non-zero size.
   std::unique_ptr<MemoryBuffer> F1;
-  if (error_code ec = MemoryBuffer::getFile(NameA, F1)) {
+  if (std::error_code ec = MemoryBuffer::getFile(NameA, F1)) {
     if (Error)
       *Error = ec.message();
     return 2;
   }
   std::unique_ptr<MemoryBuffer> F2;
-  if (error_code ec = MemoryBuffer::getFile(NameB, F2)) {
+  if (std::error_code ec = MemoryBuffer::getFile(NameB, F2)) {
     if (Error)
       *Error = ec.message();
     return 2;