[gn build] Port 3e1d4ec

Author: llvmgnsyncbot

llvm/utils/gn/secondary/llvm/lib/ExecutionEngine/Orc/BUILD.gn

@@ -39,7 +39,9 @@ static_library("Orc") {
     "LLJIT.cpp",
     "Layer.cpp",
     "LazyReexports.cpp",
+    "LoadRelocatableObject.cpp",
     "LookupAndRecordAddrs.cpp",
+    "MachO.cpp",
     "MachOPlatform.cpp",
     "Mangling.cpp",
     "MapperJITLinkMemoryManager.cpp",