Modify ReentrancyGuard to reduce contract size

contracts/security/ReentrancyGuard.sol

@@ -40,24 +40,30 @@ abstract contract ReentrancyGuard {
         _status = _NOT_ENTERED;
     }
 
-    /**
-     * @dev Prevents a contract from calling itself, directly or indirectly.
-     * Calling a `nonReentrant` function from another `nonReentrant`
-     * function is not supported. It is possible to prevent this from happening
-     * by making the `nonReentrant` function external, and making it call a
-     * `private` function that does the actual work.
-     */
-    modifier nonReentrant() {
+    function _nonReentrant() private {
         // On the first call to nonReentrant, _notEntered will be true
         require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
 
         // Any calls to nonReentrant after this point will fail
         _status = _ENTERED;
+    }
 
-        _;
-
+    function _nonReentrant2() private {
         // By storing the original value once again, a refund is triggered (see
         // https://eips.ethereum.org/EIPS/eip-2200)
         _status = _NOT_ENTERED;
     }
+
+    /**
+     * @dev Prevents a contract from calling itself, directly or indirectly.
+     * Calling a `nonReentrant` function from another `nonReentrant`
+     * function is not supported. It is possible to prevent this from happening
+     * by making the `nonReentrant` function external, and making it call a
+     * `private` function that does the actual work.
+     */
+    modifier nonReentrant() {
+        _nonReentrant();
+        _;
+        _nonReentrant2();
+    }
 }