Add pcre status to config response

doc/protocol.rst

@@ -1600,6 +1600,7 @@ Reflection
 
     - ``music_directory``: The absolute path of the music directory.
     - ``playlist_directory``: The absolute path of the playlist directory.
+    - ``pcre``: Indicates pcre support.
 
 .. _command_commands:
 

src/command/OtherCommands.cxx

@@ -395,6 +395,10 @@ handle_config(Client &client, [[maybe_unused]] Request args, Response &r)
 	if (const auto spl_path = map_spl_path(); !spl_path.IsNull())
 		r.Fmt(FMT_STRING("playlist_directory: {}\n"), spl_path.ToUTF8());
 
+#ifdef HAVE_PCRE
+	r.Write("pcre: 1\n");
+#endif
+
 	return CommandResult::OK;
 }