* guix/pk-crypto.scm: Rename procedures, variables, etc. from
'gcry-sexp' to 'canonical-sexp'. Add comment with references.
* guix/scripts/authenticate.scm, tests/pk-crypto.scm: Adjust
accordingly.
Reported by Andreas Enge <andreas@enge.fr>.
* tests/pk-crypto.scm ("string->gcry-sexp->string"): Remove "#C0FFEE#"
from SEXPS.
("gcry-sexp-nth"): Start at index 1.