Pull up following revision(s) (requested by phx in ticket #989):
sys/arch/amiga/include/vmparam.h: revision 1.46
Reduce MAXDSIZ from 416MB back to 224MB.
Due to limitations by the current pmap implementation our virtual address
space is limited to 512MB. A MAXDSIZ of 416MB would leave only a little bit
more than 30MB for shared objects and heap allocations, so 224MB seems like
a good compromise.

(riz)