Use size_t in THManagedMapAllocator (#103331)
When reviewing the source code, I found the ptrdiff_t size in THManagedMapAllocator::THManagedMapAllocator can be changed to size_t size to avoid unnecessary casts.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/103331
Approved by: https://github.com/malfet
