Revert "Update to ToT which removed std::error_code"

This reverts commit r18853. This was already fixed by the previous
commit.

Swift SVN r18855

Author: gottesmm

Diff for: lib/Driver/Driver.cpp

@@ -818,7 +818,7 @@ static StringRef getOutputFilename(const JobAction *JA,
     // the top level.
     StringRef Stem = llvm::sys::path::stem(BaseName);
     StringRef Suffix = types::getTypeTempSuffix(JA->getType());
-    llvm::error_code EC =
+    std::error_code EC =
         llvm::sys::fs::createTemporaryFile(Stem, Suffix, Buffer);
     if (EC) {
       Diags.diagnose(SourceLoc(),

Diff for: lib/IRGen/IRGenDebugInfo.cpp

@@ -500,7 +500,7 @@ llvm::DIFile IRGenDebugInfo::getOrCreateFile(const char *Filename) {
   StringRef File = BumpAllocatedString(llvm::sys::path::filename(Filename));
   llvm::SmallString<512> Path(Filename);
   llvm::sys::path::remove_filename(Path);
-  llvm::error_code ec = llvm::sys::fs::make_absolute(Path);
+  std::error_code ec = llvm::sys::fs::make_absolute(Path);
   // Basically ignore any error.
   assert(ec == std::error_code());
   (void)ec; // Silence the unused variable warning

Diff for: tools/driver/driver.cpp

@@ -54,7 +54,7 @@ int main(int argc_, const char **argv_) {
 
   llvm::SmallVector<const char *, 256> argv;
   llvm::SpecificBumpPtrAllocator<char> ArgAllocator;
-  llvm::error_code EC = llvm::sys::Process::GetArgumentVector(
+  std::error_code EC = llvm::sys::Process::GetArgumentVector(
       argv, llvm::ArrayRef<const char *>(argv_, argc_), ArgAllocator);
   if (EC) {
     llvm::errs() << "error: couldn't get arguments: " << EC.message() << '\n';