libcurl is added as dependency for gnupg-util to avoid a dependency
error.

The following invalid configuration options are removed:
  --disable-ftp
  --enable-fake-curl

Fixes: 0a61d56eb3 ("utils/gnupg: add new package gnupg-utils")
Reported-by: Hannu Nyman <hannu.nyman@iki.fi>
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>