Use references now that it is natural to do so.

The linker never takes ownership of a module or changes which module it
is refering to, making it natural to use references.

llvm-svn: 254449
diff --git a/llvm/tools/bugpoint/BugDriver.cpp b/llvm/tools/bugpoint/BugDriver.cpp
index d0731f5..39887d5 100644
--- a/llvm/tools/bugpoint/BugDriver.cpp
+++ b/llvm/tools/bugpoint/BugDriver.cpp
@@ -132,7 +132,7 @@
     if (!M.get()) return true;
 
     outs() << "Linking in input file: '" << Filenames[i] << "'\n";
-    if (Linker::LinkModules(Program, M.get()))
+    if (Linker::linkModules(*Program, *M))
       return true;
   }