This is the first step of JDK-8234693 Consolidate CDS static and dynamic archive dumping code

Currently the static archive has 4 regions, in the order of MC,RW,RO,MD, but the dynamic archive has 3 regions, in the order of RW,RO,MC

The difference in the number and ordering causes special handling code, e.g.,
http://hg.openjdk.java.net/jdk/jdk/file/f33197adda9a/src/hotspot/share/memory/metaspaceShared.cpp#l2303

The MD region is used only for the cloned CPP vtables. It's safe to move these into the MC region.

Also, for c++ vtable patching, static archive MetaspaceShared::patch_cpp_vtable_pointers(), but dynamic archive uses MetaspaceShared::fix_cpp_vtable_for_dynamic_archive(). We should consolidate the code to just use the latter.