guile-gcrypt: update to version 0.4.0

ChangeLog:

* Changes in 0.4.0 (since 0.3.0)
** ���base64-encode��� and ���base64-decode��� now let you optionally control padding
** New supported algorithms added to (gcrypt hash)
** New supported algorithms added to (gcrypt mac)
** Improvements and fixes to the manual
* Changes in 0.3.0 (since 0.2.1)
** ���sexp->canonical-sexp->sexp��� now accepts integers
** (gcrypt common) exports ���error/��� constants and error handling procedures
** ���verify��� now throws upon errors other than ���error/bad-signature���
** (gcrypt hmac) and (gcrypt hash) export bindings for their syntax literals
** New ���hash-algorithm-name��� and ���mac-algorithm-name��� procedures

(nikita)