Prefer /usr/share/metainfo as default path for metainfo files

This makes asglib align with the AppStream spec, which sees
/usr/share/metainfo as the canonical location for storing metadata, and
/usr/share/appdata as legacy (but still must-be-supported) location.

Signed-off-by: Richard Hughes <richard@hughsie.com>

client/as-util.c

@@ -3857,7 +3857,7 @@ as_util_split_appstream (AsUtilPrivate *priv, gchar **values, GError **error)
 		}
 
 		/* save to a file */
-		path = g_build_filename (destdir, "usr", "share", "appdata", fn, NULL);
+		path = g_build_filename (destdir, "usr", "share", "metainfo", fn, NULL);
 		g_debug ("saving %s as %s", id, path);
 		file_app = g_file_new_for_path (path);
 		if (!as_app_to_file (app, file_app, NULL, error))

data/appdata-xml.m4

@@ -36,7 +36,7 @@ AU_DEFUN([APPDATA_XML],
          AS_IF([test "x$enable_appdata_validate" = "xyes"],
                [AC_MSG_ERROR([AppData validation was requested but appstream-util was not found])])])
 
-  AC_SUBST([appdataxmldir], [${datadir}/appdata])
+  AC_SUBST([appdataxmldir], [${datadir}/metainfo])
 
   APPDATA_XML_RULES='
 .PHONY : uninstall-appdata-xml install-appdata-xml clean-appdata-xml