[tree-ssa] testsuite runs with a new pass

[Andrew MacLeod]

So what exactly is it we do when a new pass is added to make the
testsuites work?  Im getting unresolved failures in the testsuite
because they seem to depend on specific dump names.  ie:

< ERROR: gcc.dg/tree-ssa/ssa-dom-thread-1.c: error executing dg-final:
couldn't open "ssa-dom-thread-1.c.t20.dom1 ssa-dom-thread-1.c.t21.dom1":
no such file or directory
< UNRESOLVED: gcc.dg/tree-ssa/ssa-dom-thread-1.c: error executing
dg-final: couldn't open "ssa-dom-thread-1.c.t20.dom1
ssa-dom-thread-1.c.t21.dom1": no such file or directory

All the dump names have ben shifted by one because of a new one....

I presume I am missing something simple...

Andrew