app_server: fix stack overflow crash if too many windows are tiled

Fixes #15796.

Change-Id: I24c29215116e6bad37f0a56e141d6fc26bbe4fb2
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2680
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

src/servers/app/decorator/TabDecorator.cpp

@@ -439,6 +439,8 @@ TabDecorator::_DistributeTabSize(float delta)
 	}
 
 	float minus = ceilf(std::min(maxTabSize - secMaxTabSize, delta));
+	if (minus < 1.0)
+		return;
 	delta -= minus;
 	minus /= nTabsWithMaxSize;