Introduce xbps_repo_get_pkg_plist() and use it in xbps-query -R.

lib/repo.c

@@ -190,6 +190,22 @@ xbps_repo_get_pkg(struct xbps_repo *repo, const char *pkg)
 	return NULL;
 }
 
+prop_dictionary_t
+xbps_repo_get_pkg_plist(struct xbps_handle *xhp, prop_dictionary_t pkgd,
+		const char *plist)
+{
+	prop_dictionary_t bpkgd;
+	char *url;
+
+	url = xbps_repository_pkg_path(xhp, pkgd);
+	if (url == NULL)
+		return NULL;
+
+	bpkgd = xbps_get_pkg_plist_from_binpkg(url, plist);
+	free(url);
+	return bpkgd;
+}
+
 static prop_array_t
 revdeps_match(struct xbps_repo *repo, prop_dictionary_t tpkgd, const char *str)
 {