Fix a check that was attempting to see if an object file was in memory.

[clayborg]

Summary

Checking if an object file is in memory should use the ObjectFile::IsInMemory(), not test ObjectFile::BaseAddress(). ObjectFile::BaseAddress() is designed to be overridden by all classes and is for mach-o, ELF and COFF plug-ins. They find the header base adddress and return that as a section offset address. The default implementation of ObjectFile::BaseAddress() does try and make an Address() from the ObjectFile::m_memory_addr, but I switched it to a correct function call.

lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp

if (add_section && (const_segname || is_core)) {
     segment_sp->SetIsEncrypted(segment_is_encrypted);
     m_sections_up->AddSection(segment_sp);
     segment_sp->SetPermissions(segment_permissions);
     if (add_to_unified)
       context.UnifiedList.AddSection(segment_sp);
   } else if (unified_section_sp) {
     if (is_dsym && unified_section_sp->GetFileAddress() != load_cmd.vmaddr) {
       // Check to see if the module was read from memory?
-      if (module_sp->GetObjectFile()->GetBaseAddress().IsValid()) {
+      if (module_sp->GetObjectFile()->IsInMemory()) {
         // We have a module that is in memory and needs to have its file
         // address adjusted. We need to do this because when we load a file
         // from memory, its addresses will be slid already, yet the addresses
         // in the new symbol file will still be unslid.  Since everything is
         // stored as section offset, this shouldn't cause any problems.
 
         // Make sure we've parsed the symbol table from the ObjectFile before
         // we go around changing its Sections.