[tree-ssa] VLA fixes

[law@redhat.com]

In message <1045866129.8671.95.camel@shadowfax>, Diego Novillo writes:
 >On Fri, 2003-02-21 at 17:18, law@redhat.com wrote:
 >
 >> This fixes a handful of testsuite failures where DCE was deleting
 >> expressions needed to size the VLA.    Whee.
 >> 
 >Which failure was this?  I thought I had caught all the VLA-related
 >failures when I added set_vla_decl.  Guess I wasn't paying too much
 >attention :)
execute/20020412-1.c's execution failures.

Interestingly enough 20020412-1.c has a compile failure that I'm still
looking at.  It looks like gimplification has created something the
backend doesn't grok.  Fun.
jeff