Free objects that were dynamically allocated in libcrypto with OPENSSL_free().

Free objects that were dynamically allocated in libcrypto with OPENSSL_free().
When linking against libressl, OPENSSL_malloc() is just a wrapper around malloc()
so regular free() is safe. Other implementations allow switching to a different
allocator where free() could result in a possible heap corruption.

Report and initial fix by dropk1ck (gh #92)
ok tb@