#163 envfrom buffer too small

[A. Schulze]

http://www.trusteddomain.org/pipermail/opendmarc-users/2016-May/000643.html point to an issue where SPF check fail. Inspecting the code I found a buffer too small.

OpenDKIM uses a buffer of 256 byte to receive envelope sender. OpenDMARC define only 64 byte.
The attached patch increase the buffer size and mention references to similiar OpenDKIM code.

[Murray S. Kucherawy]

Fixed; I used BUFRSZ instead of a fixed value here.

[Murray S. Kucherawy]

Fixed in 1.3.2.