RakLibServer: disable GC

GC is not required for RakLib as it doesn't generate any unmanaged cycles.
Cycles in general do exist (e.g. Server <-> ServerSession), but these are
explicitly cleaned up, so GC wouldn't have any useful work to do.

src/network/mcpe/raklib/RakLibServer.php

@@ -38,7 +38,7 @@
 use raklib\server\SimpleProtocolAcceptor;
 use raklib\utils\ExceptionTraceCleaner;
 use raklib\utils\InternetAddress;
-use function gc_enable;
+use function gc_disable;
 use function ini_set;
 
 class RakLibServer extends Thread{
@@ -82,10 +82,9 @@ public function startAndWait(int $options = NativeThread::INHERIT_NONE) : void{
 	}
 
 	protected function onRun() : void{
-		//TODO: switch to manually triggered GC
-		//the best time to do it is between ticks when the server would otherwise be sleeping, but RakLib's current
-		//design doesn't allow this as of 1.1.1
-		gc_enable();
+		//RakLib has cycles (e.g. ServerSession <-> Server) but these cycles are explicitly cleaned up anyway, and are
+		//very few, so it's pointless to waste CPU time on GC
+		gc_disable();
 
 		ini_set("display_errors", '1');
 		ini_set("display_startup_errors", '1');