Fix memory leak

Fixes oss-fuzz #44685

Author: dstogov

Zend/tests/generators/errors/resume_running_generator_error_002.phpt

@@ -0,0 +1,17 @@
+--TEST--
+Memory leak when resume an already running generator
+--FILE--
+<?php
+function gen() {
+    $g = yield;
+    $g->send($g);
+}
+$gen = gen();
+try {
+    $gen->send($gen);
+} catch (Throwable $e) {
+    echo $e->getMessage() . "\n";	
+}
+?>
+--EXPECT--
+Cannot resume an already running generator

Zend/zend_generators.c

@@ -924,6 +924,7 @@ ZEND_METHOD(Generator, send)
 	root = zend_generator_get_current(generator);
 	/* Put sent value in the target VAR slot, if it is used */
 	if (root->send_target) {
+		zval_ptr_dtor(root->send_target);
 		ZVAL_COPY(root->send_target, value);
 	}