Use make_unique. NFC.

llvm-svn: 243988
diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index d70589f..68ad6d7 100644
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -61,7 +61,7 @@
 }
 
 static std::unique_ptr<InputFile> createFile(MemoryBufferRef MB) {
-  return std::unique_ptr<InputFile>(new ObjectFile<object::ELF64LE>(MB));
+  return make_unique<ObjectFile<object::ELF64LE>>(MB);
 }
 
 void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {