[lldb] Fix use after free on ModuleList::RemoveSharedModuleIfOrphaned

This fixes a potential use after free where
ModuleList::RemoveSharedModuleIfOrphaned ->
SharedModuleList::RemoveIfOrphaned -> SharedModuleList::RemoveFromMap
would potentially dereference a freed pointer. This fixes it by not
calling ModuleList::RemoveSharedModuleIfOrphaned at all if the pointer
was just freed.

Author: augusto2112

lldb/source/Target/Target.cpp

@@ -2564,9 +2564,12 @@ ModuleSP Target::GetOrCreateModule(const ModuleSpec &orig_module_spec,
           m_images.Append(module_sp, notify);
 
         for (ModuleSP &old_module_sp : replaced_modules) {
+          auto use_count = old_module_sp.use_count();
           Module *old_module_ptr = old_module_sp.get();
           old_module_sp.reset();
-          ModuleList::RemoveSharedModuleIfOrphaned(old_module_ptr);
+          // If the use count was one, this was not in the shared module list.
+          if (use_count > 1)
+            ModuleList::RemoveSharedModuleIfOrphaned(old_module_ptr);
         }
       } else
         module_sp.reset();