This is my Driver refactoring patch. 

The major changes are:
1) LinkerOptions has been merged into TargetInfo
2) LinkerInvocation has been merged into Driver
3) Drivers no longer convert arguments into an intermediate (core) argument 
   list, but instead create a TargetInfo object and call setter methods on 
   it. This is only how in-process linking would work. That is, you can 
   programmatically set up a TargetInfo object which controls the linking.
4) Lots of tweaks to test suite to work with driver changes
5) Add the DarwinDriver
6) I heavily doxygen commented TargetInfo.h

Things to do after this patch is committed:
a) Consider renaming TargetInfo, given its new roll. 
b) Consider pulling the list of input files out of TargetInfo. This will 
   enable in-process clients to create one TargetInfo the re-use it with 
   different input file lists.
c) Work out a way for Drivers to format the warnings and error done in 
   core linking.

llvm-svn: 178776
diff --git a/lld/lib/ReaderWriter/Reader.cpp b/lld/lib/ReaderWriter/Reader.cpp
index 17ee4f3..9f08ed2 100644
--- a/lld/lib/ReaderWriter/Reader.cpp
+++ b/lld/lib/ReaderWriter/Reader.cpp
@@ -19,12 +19,12 @@
 }
 
 error_code Reader::readFile(StringRef path,
-                            std::vector<std::unique_ptr<File>> &result) {
+                            std::vector<std::unique_ptr<File>> &result) const {
   OwningPtr<llvm::MemoryBuffer> opmb;
   if (error_code ec = llvm::MemoryBuffer::getFileOrSTDIN(path, opmb))
     return ec;
 
   std::unique_ptr<MemoryBuffer> mb(opmb.take());
-  return this->parseFile(std::move(mb), result);
+  return this->parseFile(mb, result);
 }
 } // end namespace lld