libgpg-error: refer to network resource using https where possible

[Daniel Kahn Gillmor]

This is a simple series of patches that cleans up references in the
source to network resources, using https:// where possible instead of
http://.  the final patch actually cleans up an old FIXME comment
instead of re-pointing the results to https.  I can provde these all
in single a squashed commit if you prefer it.