Use JIT_CHECK in CopyGraph::addEdge

Summary:
This exposes the crash with test_xml_etree.  This JIT_DCHECK is scary because if
we fail it we'll crash later in the program's execution, where it's harder to
debug.

Reviewed By: yoney, jbower-fb

Differential Revision: D81512871

fbshipit-source-id: ec0c0677e0dda548f94d081b9716f8651db57892

Author: alexmalyshev

cinderx/Jit/codegen/copy_graph.cpp

@@ -16,7 +16,7 @@ CopyGraph::Node::~Node() {
 void CopyGraph::addEdge(int from, int to) {
   auto parent = getNode(from);
   auto child = getNode(to);
-  JIT_DCHECK(child->parent == nullptr, "child already has a parent");
+  JIT_CHECK(child->parent == nullptr, "child already has a parent");
   setParent(child, parent);
 }