Module summary generation fails on Windows 32bit

The module summary generation build step is run on the just built jdk (just like a bootcycle build). The recent change to only build the server JVM on 32bit Windows has already caused trouble with bootcycle builds in JDK-8160571 and JDK-8160285. Now we face a similar issue with this summary generation, which uses a fixed setting of -Xmx1100M. In JDK-8160571 we learned that this is sometimes too much for the server JVM on Windows 32bit and now we see failures because of it.