Warn when CompressedClassSpaceSize is adjusted down

[mgm3746]

If MaxMetaspaceSize is set smaller than CompressedClassSpaceSize, the JVM auto adjusts CompressedClassSpaceSize as follows: CompressedClassSpaceSize = MaxMetaspaceSize - (2 * InitialBootClassLoaderMetaspaceSize).

If CompressedClassSpaceSize is not available, assume 1g default.