Rust: add flow step for MacroStmts

Author: aibaars

rust/ql/lib/codeql/rust/dataflow/internal/DataFlowImpl.qll

@@ -202,6 +202,7 @@ private ExprCfgNode getALastEvalNode(ExprCfgNode e) {
   result = e.(ReturnExprCfgNode).getExpr() or
   result = e.(BreakExprCfgNode).getExpr() or
   result = e.(BlockExprCfgNode).getTailExpr() or
+  result = e.(MacroStmtsCfgNode).getExpr() or
   result = e.(MatchExprCfgNode).getArmExpr(_) or
   result = e.(MacroExprCfgNode).getMacroCall().(MacroCallCfgNode).getExpandedNode() or
   result.(BreakExprCfgNode).getTarget() = e