Remove comment regarding Module pass return value -- no IR change by BuildDFG

hpvm/lib/Transforms/BuildDFG/BuildDFG.cpp

@@ -67,7 +67,7 @@ bool BuildDFG::runOnModule(Module &M) {
   // Checking that we found at least one launch site
   assert((Roots.size() != 0) && "Launch site not found.");
 
-  return false; //TODO: What does returning "false" mean?
+  return false;
 }
 
 DFInternalNode *BuildDFG::getRoot() const {