CCVER=gcc46: Now builds world and kernel cleanly

CCVER=gcc46: Now builds world and kernel cleanly

Starting with gcc 4.5, sbin/restore would break on interactive.c with
the complaint that the designated length of the storage array within
the adirent union structure was not constant.  After three previous
proposals on the best way to fix it, this is the one requiring the
least code change.  (Don't count the spelling correction!)

This was the last place the breaks using WORLD_CCVER=gcc46.  The
kernel builds cleanly.  Both the gcc46-built world and kernel load
and function normally.

suggested-by: vsrinivas