Reland D75382 "[lld] Initial commit for new Mach-O backend"

With a fix for http://lab.llvm.org:8011/builders/clang-cmake-armv8-lld/builds/3636

Also trims some unneeded dependencies.
diff --git a/lld/MachO/Target.cpp b/lld/MachO/Target.cpp
new file mode 100644
index 0000000..0f70776
--- /dev/null
+++ b/lld/MachO/Target.cpp
@@ -0,0 +1,14 @@
+//===- Target.cpp ---------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "Target.h"
+
+using namespace lld;
+using namespace lld::macho;
+
+TargetInfo *macho::target = nullptr;