Code review comment for lp:~zseil/pyopenssl/util-cleanup

Here is the branch that adds error checks to the functions in util.c. The important changes are in the first changeset, subsequent changesets fix minor nits and can be dropped.

Unfortunately, I didn't find any reasonable way to test these changes. The errors would only manifest in low memory conditions, and I don't know of any tools that would reliably cause a memory allocation failure at an exact time (especially when you take Python's obmalloc into account). Maybe we could submit pyOpenSSL to Coverity's Scan <http://scan.coverity.com/>, I think that their static analysis tool is able to detect missing NULL checks.