mariadb.client: fixup build

I expect it got broken by mariadb update in PR #132916 (a160dfbf3).

pkgs/servers/sql/mariadb/default.nix

@@ -95,7 +95,7 @@ common = rec { # attributes common to both builds
     rm "$out"/bin/{mariadb_config,mysql_config}
     rm -r $out/include
     rm -r $out/lib/pkgconfig
-    rm -r $out/share/aclocal
+    rm -rf "$out"/share/aclocal
   '';
 
   passthru.mysqlVersion = "5.7";
@@ -135,7 +135,7 @@ client = stdenv.mkDerivation (common // {
   ];
 
   postInstall = common.postInstall + ''
-    rm -r "$out"/share/doc
+    rm -rf "$out"/share/doc
     rm "$out"/bin/{mysqltest,mytop}
     libmysqlclient_path=$(readlink -f $out/lib/libmysqlclient${libExt})
     rm "$out"/lib/{libmariadb${libExt},libmysqlclient${libExt},libmysqlclient_r${libExt}}