* WebAssembly: fixed SysUtils.sleep() with large timeouts causing incorrect time

  delay, due to arithmetic overflow

rtl/wasi/sysutils.pp

@@ -760,7 +760,7 @@ begin
   FillChar(subscription,SizeOf(subscription),0);
   subscription.u.tag:=__WASI_EVENTTYPE_CLOCK;
   subscription.u.u.clock.id:=__WASI_CLOCKID_MONOTONIC;
-  subscription.u.u.clock.timeout:=MilliSeconds*1000000;
+  subscription.u.u.clock.timeout:=__wasi_timestamp_t(MilliSeconds)*1000000;
   subscription.u.u.clock.precision:=1000000;
   subscription.u.u.clock.flags:=0;  { timeout value is relative }
   __wasi_poll_oneoff(@subscription,@event,1,@nevents);