Two new hard deps: gcrypt and redland

Hi,
  As new dependencies might have wider impact I thought I would write
the list with some info from IRC.

  Apparently the windows build already depends on gcrypt. The plan is to
remove the HAVE_GCRYPT and make gcrypt a hard dependency. gcrypt is
currently used to allow encrypted ODF files to be read. In the future I
hope the use of gcrypt can extend to include other privacy and tamper
protections.

  The redland stack is also on the cards to become a hard dep. Redland
is used for some RDF processing and is already shipped with the windows
build. I have compiled redland for the n810 in the past. So smaller
devices should also be fine with this dependency.