Internals: Fix cppcheck warnings; add VL_DANGLING. No functional change.

src/V3Coverage.cpp

@@ -343,7 +343,7 @@ private:
 	    // Skip all NEXT nodes under this block, and skip this if/case branch
 	    UINFO(4,"  OFF: "<<nodep<<endl);
 	    m_checkBlock = false;
-	    nodep->unlinkFrBack()->deleteTree(); nodep=NULL;
+	    nodep->unlinkFrBack()->deleteTree(); VL_DANGLING(nodep);
 	} else {
 	    if (m_checkBlock) nodep->iterateChildren(*this);
 	}