[lldb][Plugins] Reflect structure changes in ObjectContainer

Reflect recent changes made to MachO
`fileset_entry_command` struct.

Author: antoniofrighetto

lldb/source/Plugins/ObjectContainer/Mach-O-Fileset/ObjectContainerMachOFileset.cpp

@@ -158,7 +158,7 @@ ParseFileset(DataExtractor &data, mach_header header,
     if (lc.cmd == LC_FILESET_ENTRY) {
       fileset_entry_command entry;
       data.CopyData(load_cmd_offset, sizeof(fileset_entry_command), &entry);
-      lldb::offset_t entry_id_offset = load_cmd_offset + entry.entry_id;
+      lldb::offset_t entry_id_offset = load_cmd_offset + entry.entry_id.offset;
       const char *id = data.GetCStr(&entry_id_offset);
       entries.emplace_back(entry.vmaddr + slide, entry.fileoff,
                            std::string(id));