Added a break that I meant to include originally, for efficiency.  Basically
it keeps it from trying to add the same node to the node set
over and over if it matches multiple given patterns.  Also in cases where there
are a lot of patterns to be matched, and it matches an early one, this
will make the script run slightly faster.  It's more there because it logically
should be, than anything else, I mean, Python is never going to be fast ;-)

llvm-svn: 24876