Incorrect alignment in CDS related allocation code on 32-bit platforms

Problem reported by fedor.burdun@azul.com:

I've found an inconsistency in CDS related Klass* reallocating code, in method

        static void ArchiveCompactor::allocate(MetaspaceClosure::Ref* ref, bool read_only) (src/hotspot/share/memory/metaspaceShared.cpp:1122)

the alignment = BytesPerWord has been used, that is fine for 64bit platforms, but may cause problems on 32bit ones.
For example, in case of ARM gcc compiles accessors for u8/long long types using ldrd/strd instructions that requires a double-word alignment on ARMv5TE and older.

Moreover the method (although it used only for compressed oops)

        inline bool check_klass_alignment(Klass* obj) in src/hotspot/share/oops/klass.inline.hpp

checks classes to be aligned to KlassAlignment const, not to the BytesPerWord one.