Fix issue with OpenSSL and large DBs

[Red-M]

As per #21 this should fix the issue described.

[cytopia]

@Red-M this fix looks too good to be true. I will have to do some manual tests and see if it does what it is supposed to to. Thanks for this fix

[globz]

@cytopia Have you had the chance to review this fix? does it look like you will be able to merge this pull?

[mstenz]

I have tested this. -stream works only on encrypting, but not decrypting.
When decrypting a larger file this is the error message that still appears:

140321499632064:error:07069041:memory buffer routines:BUF_MEM_grow_clean:malloc failure:../crypto/buffer/buffer.c:138:
140321499632064:error:0D06B041:asn1 encoding routines:asn1_d2i_read_bio:malloc failure:../crypto/asn1/a_d2i_fp.c:191:

right now i am using this openssl version:
OpenSSL 1.1.0g 2 Nov 2017