sd-resolve: make struct addrinfo defined

src/systemd/meson.build

@@ -31,12 +31,10 @@ _not_installed_headers = '''
         sd-network.h
         sd-path.h
         sd-radv.h
+        sd-resolve.h
         sd-utf8.h
 '''.split()
 
-# The following headers do not pass tests.
-#  sd-resolve.h
-
 install_headers(
         systemd_headers,
         '_sd-common.h',

src/systemd/sd-resolve.h

@@ -17,6 +17,11 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
+/* 'struct addrinfo' needs _GNU_SOURCE */
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE 1
+#endif
+
 #include <inttypes.h>
 #include <netdb.h>
 #include <sys/socket.h>