Update CHANGES to reflect base64 fix added to 0.9.7

     Make that possible even when linking against static libraries!

     [Richard Levitte]

  *) Various fixes to base64 BIO and non blocking I/O. On write 

     flushes were not handled properly if the BIO retried. On read

     data was not being buffered properly and had various logic bugs.

     [Steve Henson]

  *) Support for single pass processing for S/MIME signing. This now

     means that S/MIME signing can be done from a pipe, in addition

     cleartext signing (multipart/signed type) is effectively streaming

 Changes between 0.9.7b and 0.9.7c  [xx XXX 2003]

  *) Various fixes to base64 BIO and non blocking I/O. On write 

     flushes were not handled properly if the BIO retried. On read

     data was not being buffered properly and had various logic bugs.

     This also affects blocking I/O when the data being decoded is a

     certain size.

     [Steve Henson]

  *) Various S/MIME bugfixes and compatibility changes:

     output correct application/pkcs7 MIME type if

     PKCS7_NOOLDMIMETYPE is set. Tolerate some broken signatures.