Internals: Use pushDelete for empty unrolls. Theoretical problem only.

src/V3Unroll.cpp

@@ -404,7 +404,7 @@ private:
 		// we'd need to initialize the variable to the initial
 		// condition, but they'll become while's which can be
 		// deleted by V3Const.
-		nodep->unlinkFrBack()->deleteTree(); VL_DANGLING(nodep);
+                pushDeletep(nodep->unlinkFrBack()); VL_DANGLING(nodep);
             } else if (forUnrollCheck(nodep, nodep->initsp(),
                                       NULL, nodep->condp(),
                                       nodep->incsp(), nodep->bodysp())) {