DSA_free(): this was causing crashes when for example an attempt was made
to handle a (currently) unsupported DH public key. Also X509_PUBKEY_set()i
wasn't checking errors from d2i_PublicKey().

1. The already released version was 0.9.1c and not 0.9.1b

2. The next release should be 0.9.2 and not 0.9.1d, because
   first the changes are already too large, second we should avoid any more
   0.9.1x confusions and third, the Apache version semantics of
   VERSION.REVISION.PATCHLEVEL for the version string is reasonable (and here
   .2 is already just a patchlevel and not major change).
tVS: ----------------------------------------------------------------------