[tree-ssa] Latent edge insertion bug

[law@redhat.com]

In message <4BC5FDFE-3598-11D8-BBD2-000A95D7CD40@apple.com>, Dale Johannesen wr
ites:
 >Doing that was mostly what I was thinking about.  If you don't bother, 
 >that leads to splitting a fair number of edges that don't really need to be 
 >split just how bad is that?
The vast majority of the time those blocks will go away before we leave
the tree-ssa path.  At the worst I would an extra jump for the RTL
CFG cleanup code to eliminate.

jeff