Rework info_to_obj routine to avoid memory leaks

[ldo]

The previous code of info_to_obj would leak memory. This rework uses structured programming to ensure that correct recovery happens on all error paths, avoiding leaks or double-frees.

plug-info_to_obj-leaks.patch.txt

[tynn]

Could you create a pull request for it?

[ldo]

No fork, sorry.