[binfo] Inline base binfo vector

[Andrew Haley]

Nathan Sidwell writes:

 > this patch places a binfo's vector of base binfos as an inline
 > trailing array, thus reducing memory fragmentation and indirection.
 > 
 > To do this, I had to hoist the three c++ specific fields to the
 > common code, thus making binfos themselves bigger for Java.
 > However, overall it is still a win. Two weeks ago I removed on word
 > from the binfo (by stopping it be a TREE_VEC), this patch removes
 > the VEC overhead of the base binfo vector (4 words), but adds 2
 > words for the new vector.  Thus saving 3 words overall (which I use
 > up with the new c++ fields).  The java saving is thus in removing
 > indirection, I hope this is satisfactory.

Seems reasonable.

Andrew.