I've committed this to the gomp4 branch.  It extends the  'oacc function' 
attribute's dimension handling to deal with routines.  With the latter we now 
use TREE_PURPOSE of the dimension list to indicate whether the routine may or 
may not spawn a partitioned loop on a particular axis.  I had to tweak the 
validate_dims hook to tell it what the outermost such axis is (or -1 for a 
non-routine).

The patch was complicated y the rather baroque handling of the routine directive 
in  the C and C++ frontends.  Now I see that handling is based on a 
misinterpretation of the specification.  I'll clean that up shortly.

nathan