Hello,

Following on from max_register_size() this provides a replacement for 
REGISTER_VIRTUAL_TYPE that uses a pre-computed table.   As the comment 
explains, REGISTER_VIRTUAL_TYPE(r) should equal REGISTER_RAW_TYPE(r) so 
instead the method is called register_type().

Post 5.3 branch patches can flush out and convert everything.  The 
architecture method will be renamed changed to gdbarch_register_type().

I'll look at committing this in a few days,

enjoy,
Andrew