XML-Security-C memory leak

[Jesse Pelton]

OpenSSLCryptoBase64::b642BN() leaks memory in the following line:

        return BN_dup(BN_bin2bn(buf, bufLen, NULL));

BN_bin2bn() allocates a BIGNUM, so there's no need to dup it, and doing
so causes the first one to leak.

This is not the only leak I'm seeing in my app, but it's the only one
I've managed to track down so far.  I'll be sure to post again if any of
the remaining leaks are in the library ;-).