Tarnum-tst

Sorry for long post but it seems that cffi is producing better C code compared to Rust one. Compiling on i686-pc-windows-gnu/rust 1.66.0/Windows 7 x64 SP1 with latest KB5022338 installed/Python 3.7...

@alex When compiling cffi build I got only two warnings, similar to these: ``` warning: C:\Python37\crypmain\src\rust\target\i686-pc-windows-gnu\release\build\cryptography-rust-74aa9bb878ed6b19\out\_openssl.c: At top level: warning: C:\Python37\crypmain\src\rust\target\i686-pc-windows-gnu\release\build\cryptography-rust-74aa9bb878ed6b19\out\_openssl.c:784:13: warning: 'ERR_load_Cryptography_OSRandom_strings' declared 'static' but never defined [-Wunused-function] warning:...

@reaperhulk No, I don't have an actual issue, I just wanted to give a feedback on this PR according to my experience. :-) And You are right, I was not...