gpg: Add "self-sigs-only" and "import-clean" to the keyserver options.

gpg: Add "self-sigs-only" and "import-clean" to the keyserver options.

* g10/gpg.c (main): Change default.
--

Due to the DoS attack on the keyeservers we do not anymore default to
import key signatures.  That makes the keyserver unsuable for getting
keys for the WoT but it still allows to retriev keys - even if that
takes long to download the large keyblocks.

To revert to the old behavior add

  keyserver-optiions  no-self-sigs-only,no-import-clean

to gpg.conf.

GnuPG-bug-id: 4607
Signed-off-by: Werner Koch <wk@gnupg.org>
(cherry picked from commit 23c978640812d123eaffd4108744bdfcf48f7c93)
(cherry picked from commit 2b7151b0a57f5fe7d67fd76dfa1ba7a8731642c6)

Gbp-Pq: Topic from-2.2.17
Gbp-Pq: Name gpg-Add-self-sigs-only-and-import-clean-to-the-keyserver-.patch