OSSL_FUNC_encoder_set_ctx_params() sets context data according to parameters
from I<params> that it recognises. Unrecognised parameters should be
ignored.
+Passing NULL for I<params> should return true.
OSSL_FUNC_encoder_settable_ctx_params() returns a constant B<OSSL_PARAM>
array describing the parameters that OSSL_FUNC_encoder_set_ctx_params()