[ext/openssl] Use BIO_reset and ERR_get_error in conjuntion
This is related to the bug in http://redmine.ruby-lang.org/issues/4879.
There are still some places in Ruby OpenSSL C code where just BIO_reset
is used but not ERR_get_error if a fallback from PEM to DER is tried or
the other way round. This might cause encoding errors to pile up and
mislead users or cause tests to fail that shouldn't.
I'd like to expose the conjunction of
as a publicly accesible macro (similar to what's in ossl_pkey.c) and
replace existing code by using it where appropriate.
Please let me know if you have any objections!