Rework based on feedback:

1. Cleaned up eventfd handling
2. Reworked socket setup code to allow other algorithms to be added in
   future
3. Fixed compile errors for static build
4. Added error to error stack in all cases of ALG_PERR/ALG_ERR
5. Called afalg_aes_128_cbc() from bind() to avoid race conditions
6. Used MAX_INFLIGHT define in io_getevents system call
7. Coding style fixes

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>