g1HeapRegionRemSet.cpp includes <cstdio> before any other includes, even before precompiled.hpp. And that file doesn't need to be included at all. We don't reference anything in the std:: namespace, instead always using the C names that are already included from <stdio.h> via globalDefinitions.

This was introduced by JDK-8017163, perhaps intended as a temporary debugging change in a fairly large change set.