Without Libgcrypt 1.5 is was not possible to use ECC keys. ECC is
major new feature and thus it does not make sense to allow building
with an older Libgcrypt without supporting ECC.
Also fixed a few missing prototypes.
We better do this once and for all instead of cluttering all future
commits with diffs of trailing white spaces. In the majority of cases
blank or single lines are affected and thus this change won't disturb
a git blame too much. For future commits the pre-commit scripts
checks that this won't happen again.
