dirmngr: Handle EAFNOSUPPORT at connect_server.
* dirmngr/http.c (connect_server): Skip server with EAFNOSUPPORT.
Cherry-pick from master commit of:
109d16e8f644da97ed9c00e6f9010a53097f587a
- GnuPG-bug-id: T4977
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>