sd-dns-resolver: move header to src/systemd

This also adds missing license header.

Follow-up for ee2108dcd5.

src/libsystemd-network/ndisc-option.h

@@ -5,6 +5,7 @@
 #include <netinet/ip6.h>
 
 #include "sd-dns-resolver.h"
+#include "sd-forward.h"
 
 #include "time-util.h"
 

src/systemd/meson.build

@@ -35,6 +35,7 @@ _not_installed_headers = [
         'sd-dhcp6-lease.h',
         'sd-dhcp6-option.h',
         'sd-dhcp6-protocol.h',
+        'sd-dns-resolver.h',
         'sd-ipv4acd.h',
         'sd-ipv4ll.h',
         'sd-lldp-rx.h',

src/systemd/sd-dns-resolver.h

@@ -1,16 +1,33 @@
-#ifndef SD_DNS_RESOLVER_H
-#define SD_DNS_RESOLVER_H
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#ifndef foosddnsresolverhfoo
+#define foosddnsresolverhfoo
+
+/***
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <https://www.gnu.org/licenses/>.
+***/
 
 #include "_sd-common.h"
 
-#include "sd-forward.h"
-
 _SD_BEGIN_DECLARATIONS;
 
+struct in_addr;
+struct in6_addr;
+
 typedef struct sd_dns_resolver sd_dns_resolver;
 
 /* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml#alpn-protocol-ids */
-typedef enum sd_dns_alpn_flags {
+__extension__ typedef enum sd_dns_alpn_flags {
         /* There isn't really an alpn reserved for Do53 service, but designated resolvers may or may not offer
          * Do53 service, so we should probably have a flag to represent this capability. Unfortunately DNR
          * does not indicate the status to us. */
@@ -38,4 +55,4 @@ _SD_DEFINE_POINTER_CLEANUP_FUNC(sd_dns_resolver, sd_dns_resolver_unref);
 
 _SD_END_DECLARATIONS;
 
-#endif /* SD_DNS_RESOLVER_H */
+#endif