Fix bug in base64 bios during write an non blocking I/O: if the write fails when flushing the buffer return the value to the application so it can retry.
Fix bug in base64 bios during write an non blocking I/O:
if the write fails when flushing the buffer return the
value to the application so it can retry.

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl