When HAVE_YASSL is defined (due to cmake -DWITH_SSL=bundled
or otherwise), mysys_ssl/my_crypt.cc will #include "yassl.cc"
from the same directory.

When MariaDB 10.2 or later is compiled with GCC 8 and optimizations
are enabled, then the check
  if (iv)
in EVP_CipherInit_ex() can be wrongly optimized away.
The reason appears to be that __attribute__((nonnull)) is attached
to the variable iv, because there is a (no-op) call
memcpy(oiv, iv, ivlen=0) earlier in the code path.

It is possible that this started failing after the code was
refactored in MDEV-10332 (MariaDB 10.2.6). In MariaDB 10.1,
there is a similar memcpy() call in MyCTX_nopad::init(),
but the code appears to work fine.