AMDGPU: Use lld as the linker again

Summary:
Now that LLVM is emitting version 2 of the AMD code object, we can
start using lld again for linking instead of our custom tool.

Reviewers: arsenm, kzhuravl

Subscribers: rafael, cfe-commits

Differential Revision: http://reviews.llvm.org/D19952

llvm-svn: 268648
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index c688763..3b639bc 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -6786,6 +6786,8 @@
   std::string Linker = getToolChain().GetProgramPath(getShortName());
   ArgStringList CmdArgs;
   AddLinkerInputs(getToolChain(), Inputs, Args, CmdArgs);
+  CmdArgs.push_back("-shared");
+  CmdArgs.push_back("-o");
   CmdArgs.push_back(Output.getFilename());
   C.addCommand(llvm::make_unique<Command>(JA, *this, Args.MakeArgString(Linker),
                                           CmdArgs, Inputs));